01 What makes it unique
The 3900HBLR is Sandpiper’s 2026 flagship and the line’s statement plan. The “HBLR” marks a rear living great room built for relaxing and working: a chaise lounge, a sofa, an entertainment center with an electric fireplace, a hidden pantry, a butler pantry, a half bath, a waterfall-island kitchen and — new for 2026 — a standard desk and mobile workstation with a WiFi booster, the only plan in the line built for remote work. A 65-inch television (the line’s biggest), washer and dryer and a king front master are standard, under three slide-outs. It rides the full Sandpiper build: a cambered powder-coated frame, a single tandem 7,000-pound axle rating, an automatic electric level-up system and 200-watt solar.
Forest River lists a published 16,085-pound GVWR against the 13,284-pound dry weight, which leaves a 2,801-pound payload and a 2,085-pound dry pin, on tandem 7,000-pound axles. Its holding tanks are the biggest in the line — a 136-gallon grey tank and a 104-gallon black tank — for the longest stays off hookups. Two 15,000-BTU air conditioners (prepped for a third), a 60,000-BTU tankless water heater, a 40,000-BTU furnace, heated holding tanks and an 84-inch ceiling are standard, under dual 12-foot and 18-foot awnings.
At a starting MSRP around $108,000, with US street pricing well below the placard (units have advertised in the $70,000s), it is the rear-living, work-from-anywhere Sandpiper. For a couple who wants a residential great room, a standard mobile workstation, the line’s biggest tanks and its only 65-inch television — and who tows with a properly rated three-quarter-ton or larger truck — the 3900HBLR is the line’s flagship.
02 Full specifications
Dimensions
- Exterior length
- 42' 9"
- Exterior width
- 8' 0"
- Exterior height
- 13' 4"
- Interior height
- 7' 0"
Weights
- Dry / unit base weight (UVW)
- 13,284 lbs
- GVWR (max loaded)
- 16,085 lbs
- Net cargo / payload (CCC)
- 2,801 lbs
- Dry pin (hitch) weight
- 2,085 lbs
Capacities
- Fresh water
- 50 gal
- Grey water
- 136 gal
- Black water
- 104 gal
- Refrigerator
- 16 cu ft
Construction
- Frame
- Cambered powder-coated frame · rust prohibitor · underbelly armor
- Walls
- Laminated sidewalls · R-10 2" sidewall · welded aluminum-framed vacuum-bonded
- Roof
- Full walk-on roof · 3/8" decking · 5" truss rafters
- Underbelly
- Underbelly armor · 12V heated holding tanks · enclosed
Running gear
- Axles
- 2 (7,000 lb tandem)
- Hitch
- Fifth-wheel (in-bed) · 2" accessory receiver (where available)
- Brakes
- Anti-lock (ABS) · Lippert auto-adjust
- Tires
- Goodyear Radial · upgraded aluminum rims · TPMS
Galley & bath
- Cooktop
- 3-burner gas range · 24" oven · 30" OTR microwave
- Refrigerator
- 16 cu ft
- A/C
- 30,000 BTU (dual 15K, prepped for 3rd)
- Water heater
- 60,000-BTU tankless · on-demand
Sleeping & layout
- Sleeps
- 4
- Slides
- 3
- Entries
- 1
- Awnings
- 2 (12' & 18')
- Primary bed
- King
03 The Sandpiper floorplan family
Sandpiper is Forest River's premium-mainstream full-size fifth wheel — a step below the Cedar Creek and Riverstone luxury lines and a cross-shop against Grand Design's Reflection and Keystone's Cougar. The 2026 retail fifth-wheel line runs to seven floorplans, and all seven are profiled here in full. The 3900HBLR on this page is highlighted; each other plan links to its own page.
| Floorplan | Nominal | Sleeps | Notable |
|---|---|---|---|
| 3710HBFB | 43 ft | 7 | Front bunkhouse, bath-and-a-half, rear bath |
| 3844QUAD | 43 ft | 7 | Quad bunks + island, outside kitchen, five slides |
| 3900HBLR | 43 ft | 4 | Rear living + mobile workstation, 2026 flagship |
| 4003MB | 43 ft | 8 | Middle bunkhouse, front master + rear living + loft |
| 4002FB | 43 ft | 6 | Two full baths + two bedrooms + loft, dual entry |
| 3990FL | 44 ft | 8 | Front living + loft-and-a-half, biggest payload |
| 3800RK | 44 ft | 4 | Rear kitchen, theater seating, washer/dryer standard |
Sandpiper is Forest River's premium-mainstream full-size fifth wheel — a step below the Cedar Creek and Riverstone luxury lines and a cross-shop against Grand Design's Reflection and Keystone's Cougar. The 2026 retail fifth-wheel line runs to seven floorplans, all profiled here; two further plans, the 3370RLS and 3550BH, are Dealer Stock Only and are listed on the hub but not profiled. Every plan rides on a cambered powder-coated frame with a single tandem 7,000-pound axle rating, Goodyear Radial tires with ABS and Lippert auto-adjust brakes, an automatic electric level-up system and 200-watt solar, and ships with a 16-cubic-foot 12-volt refrigerator, two 15,000-BTU air conditioners (prepped for a third), a 60,000-BTU tankless water heater, an 84-inch ceiling and a 50-inch smart television (65-inch on the 3900HBLR) as standard. Hitch weight, GVWR, UVW and CCC are published per plan on the Forest River factory pages, and each plan's UVW plus CCC equals its GVWR exactly. UVW is a factory estimated average; real loaded pin weights run higher — always weigh the loaded coach and confirm against your truck's payload and rear-axle ratings. Sandpiper is badge-engineered as the Sierra, built side-by-side on the same line with only the decals different.
04 What owners & reviewers report
New-for-2026 flagship
The line’s newest plan — a rear-living great room with a chaise, a sofa, a fireplace entertainment center and a 65-inch television, the biggest in the line.
Standard mobile workstation
A standard desk and mobile workstation with a WiFi booster — the only Sandpiper built for remote work, with a hidden and a butler pantry alongside.
Biggest grey + black tanks
A 136-gallon grey and a 104-gallon black tank — the largest in the line for the longest stays off hookups — plus standard washer and dryer.
Couple’s plan, not a bunk plan
With a front king master and a rear great room it sleeps four — a couple’s coach rather than a family bunkhouse (some sofa-only builds are listed as sleeping three).
05 How it compares
The rear-kitchen plan — a residential galley at the back instead of a rear living great room.
Grand Design’s big rear-living Reflection — the mainstream-luxury-FW cross-shop.
Forest River’s luxury rear-living fifth wheel — a tier above, heavier and far pricier.