01 What makes it unique
The 4003MB is Sandpiper’s middle-bunkhouse plan, and the one that tucks the kids’ beds amidships. Its “MB” marks a middle bunkhouse set between a private front master and a rear living area, with bunk beds and a loft for extra sleepers, a mid kitchen island with a hidden pantry, a free-standing dinette option and an outside kitchen. It sleeps eight under four 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 15,500-pound GVWR against the 12,609-pound dry weight, which leaves a 2,891-pound payload and the lowest dry pin in the line at 2,010 pounds, on tandem 7,000-pound axles. 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, an 84-inch ceiling, a 50-inch smart television and washer/dryer prep are standard, under dual 10-foot-8-inch and 20-foot awnings.
At a starting MSRP around $95,000, with US street pricing well below the placard (commonly in the high $60,000s to low $70,000s), it is the middle-bunkhouse Sandpiper. For a family that wants the kids amidships, a private front master, a rear living area and an outside kitchen — with the line’s lowest pin for easier truck matching — the 4003MB is the line’s eight-sleeper bunkhouse.
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)
- 12,609 lbs
- GVWR (max loaded)
- 15,500 lbs
- Net cargo / payload (CCC)
- 2,891 lbs
- Dry pin (hitch) weight
- 2,010 lbs
Capacities
- Fresh water
- 50 gal
- Grey water
- 100 gal
- Black water
- 50 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
- 8
- Slides
- 4
- Entries
- 1
- Awnings
- 2 (10'8" & 20')
- 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 4003MB 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
Middle bunkhouse + rear living
Bunks and a loft amidships between a front master and a rear living area — sleeping eight with the living space kept separate from the beds.
Lowest pin in the line
A 2,010-pound dry pin — the lightest king-pin weight of any Sandpiper, the easiest in the line to match to a truck’s rear axle.
Mid island + hidden pantry + outside kitchen
A mid kitchen island with a hidden pantry, a free-standing dinette option and a standard outside kitchen — a galley built for a crowd.
Wants a three-quarter-ton+ truck
At nearly 43 feet on a 15,500-lb GVWR with tandem 7K axles, confirm a properly rated three-quarter-ton or larger truck’s payload and rear axle.
05 How it compares
The other big plan — two full baths and two bedrooms instead of a middle bunkhouse and rear living.
Keystone’s big family Cougar — a full-size bunkhouse fifth wheel in the same tier.
Forest River’s luxury bunkhouse fifth wheel — a tier above, heavier and far pricier.