2026 Forest River Riverstone421FK

The 421FK is the cook’s plan. Its galley moves to the front of the coach, up in the raised section over the pin, where a full front kitchen with an island looks out under the front-cap windows, with six slide-outs opening the main level and a private rear bedroom with a king bed behind it. Dovetail drawers, a step-storage stair and the standard 18-cubic-foot French-door refrigerator carry the residential kitchen brief. It rides the full Riverstone build: a 102-inch-wide fully-welded frame, tandem 8,000-pound axles and an automatic six-point hydraulic level-up system.

Forest River lists a published 24,000-pound GVWR against the 18,786-pound dry weight, leaving a 5,214-pound payload and a 3,635-pound dry pin — the highest in the line. Its holding tanks are skewed to the galley with a 120-gallon grey tank, the largest in the line. Two 15,000-BTU heat-pump air conditioners, a Truma AquaGo tankless water heater, a Splendide stackable washer and dryer, a Fisher & Paykel dishwasher, 200-watt solar with a 2,000-watt inverter and a 65-inch living-room Samsung television are standard, under dual 16-foot awnings.

At a starting MSRP around $214,000, with US street pricing well below the placard, it is the front-kitchen Riverstone. For a couple who cooks and wants a bright front galley with an island, the line’s biggest grey tank and a private rear bedroom — and who tows with a one-ton truck rated for the highest pin in the line — the 421FK is the cook’s plan.

Riverstone is Forest River's top-luxury full-profile fifth wheel — a step above Cedar Creek and a cross-shop against the upper trims of Keystone's Montana and Grand Design's Solitude. The 2026 fifth-wheel line runs to seven floorplans, and all seven are profiled here in full. The 421FK on this page is highlighted; each other plan links to its own page.

This floorplan carries its water comfortably. A full 79-gallon fresh tank is roughly 13% of the 5,214-pound cargo capacity, leaving the 421FK with a usable gear budget even when you tow full.

The published dry pin weight of 3,635 pounds is 19% of this floorplan’s 18,786-pound dry weight. Fifth-wheel pin weight rides in the bed of the truck, so it comes off payload rather than off tow rating — and it rises with the trailer as you load it, not in proportion to what you put over the axles.

Nothing above changes the ceiling. Loaded to its 24,000-pound GVWR the 421FK is towing 5,214 pounds more than its 18,786-pound dry figure, and that is the number your vehicle has to be rated for — not the brochure weight.

Tank balance is generous here: 79 gallons of fresh against 120 grey and 40 black, so waste capacity keeps pace with supply and the fresh tank is the constraint that ends a dry stay.

Ranked by GVWR, the 421FK sits 6 of 7 in the Riverstone line: 24,000 pounds against a line that runs from 18,975 to 24,000 pounds. That position is the useful thing to know, because the plans immediately either side of it are the real alternatives.

Either side of it in the same line: Riverstone 420RE matches it exactly at 24,000 lb GVWR; and Riverstone 425FO matches it exactly at 24,000 lb GVWR.

2 other Riverstone plans share this floorplan’s 24,000 lb GVWR, so the ranking above separates plans that tow to the same ceiling. On a shared chassis the figure that actually differs between them is cargo capacity and where the weight sits, not the rating.

Against the 421FK: the Momentum 392M is 500 lb lighter and 2 ft longer and sleeps 5 more; the Solitude 414LJMJ is 500 lb lighter and 1 ft shorter and sleeps 2 more; the Model G 3950 is 1,000 lb lighter and 1 ft longer and sleeps 4 more. Those are differences in the published numbers only — what they cost, how they are built and how they live are separate questions each of those pages answers on its own terms.

Those are the nearest fifth wheels from other lines by weight — one per line, picked by proximity on that figure and nothing else. They are listed so the same tow vehicle can be checked against real alternatives, not because they are equivalent inside; layout, build and price diverge sharply across that group.

For scale, the Riverstone floorplans profiled here run 16,511 to 19,271 pounds dry and 42 to 45 feet of exterior length across 7 plans. Where a floorplan falls in that spread usually says more about which vehicle can tow it, and which site it fits, than the layout name does.

Every profiled floorplan in this line, with the full weight table, is on the Riverstone line hub.

This catalog tracks 18 specification fields per floorplan. Named sources publish 18 of them for the 421FK. The rest are not shown, because the alternative is reading a figure across from a sibling floorplan or from what the segment usually does — and a number nobody published is worth less than an admitted gap.

Not published for this floorplan: tire size (a tire description is published, a size is not). If you find one of these in a manufacturer document for this plan, it belongs on this page.

The completeness figure at the foot of this page (98%) measures the same thing on the full field set: it is a measurement of how much this floorplan’s manufacturer publishes, not of how much research went into the page.

How every figure here was sourced and checked is set out on the methodology page.