Havnby CloudCore Diagonal Review: The Truck-Bed Geometry Trick
A short truck bed is too short to sleep straight — and long enough diagonally. Havnby built a mattress around that one geometric fact, EV pickups included.
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Truck people have argued about short-bed sleeping forever: tailgate down and feet in the weather, plywood platforms, or surrender to a rooftop tent. Havnby's answer is the kind that seems obvious only after someone builds it — stop fighting the bed's length and use its diagonal.
The geometry
A short bed that measures 5'6" straight measures well over six feet corner to corner. The CloudCore Diagonal is cut to occupy exactly that line: full stretch-out length for one sleeper, with the leftover triangle staying available for a cooler, recovery boards, or the boots you don't want inside your bedding. It's the rare product whose entire pitch is one true geometric sentence.
The build
Family recipe, truck spec: adjustable air support under a 4-inch foam core — thicker foam than the SUV CloudCores, because a truck bed's floor is harder and colder than any folded seat. Per-truck variants cover the F-150, the electric Lightning, and the Super Duty widths. As with any open-bed sleeping, the mattress handles comfort; weather is the job of your topper, shell or tarp.
The EV-truck footnote
We're an EV camping site at heart, so: the Lightning variant matters. Electric pickups pair this mattress with onboard AC power — fridge, lights, heated blanket, all running silent off the traction battery — which turns a $299 mattress into most of a camper conversion. The same logic powers our Rivian R2 coverage and the EV setup guide.
Solo truck campers: this is the smart money at about $269 with the AWD code. Couples: a full-width mattress on a platform, and our general ranking is the place to start.
Full specifications
Havnby CloudCore Diagonal for Trucks
Pros
- Diagonal layout gives a solo sleeper full length in a short bed — no tailgate-down tricks
- 4-inch foam core over adjustable air support
- Per-truck variants, including the electric F-150 Lightning
- The unclaimed triangle keeps your gear in the bed with you
Cons
- Solo by design — two sleepers need a full-bed solution
- An open truck bed still needs a topper or shell for weather
- Type
- Air + 4 in foam core
- Layout
- Diagonal, solo
- Fits
- F-150, Lightning, Super Duty
- Leaves
- Gear triangle in the bed
Save 10% with code AWD — verified July 2026
Frequently asked questions
- Why diagonal?
- Pythagoras. A 5½-foot short bed defeats anyone taller lying straight, but its corner-to-corner measurement clears six feet comfortably. The Diagonal claims that line and shapes the mattress around it, which no rectangular pad can do without wasting the geometry.
- Does it work in an F-150 Lightning?
- It's a listed variant — and the Lightning might be the best truck camping platform going: the same bed geometry plus Pro Power Onboard running your fridge, lights and heater from the traction battery. It's the truck-world version of the EV camping argument we make for Teslas and the Rivian R2.
About AWD Camper Team
AWD Camper Team researches car camping and EV gear the honest way: manufacturer specifications, long-running owner threads and retailer reviews, cross-checked against each other. Where gear has been used first-hand an article says so explicitly — where it hasn't, we don't pretend otherwise.