Camping Interior Flooring (Vinyl)
HarryMann: The non-slip (safety) varieties of vinyl floor are best (like you find behind a pub bar), and its only a few metres, these often come in 2 metre widths as well as 4, ideal. Altro is the original, but many cheaper copies around (e.g. Tarkett, Polyflor)
Also, you will find traders at many camper shows, with many suitable offcuts of high-quality altro/polyfloor type non-slip vinyls (£20 normally covers it)
The timber base - I'd go for about 8~10mm ply every time, why go thicker over a small area? Middle grade (hardwood faced) and give it a quick coat of clear wood sealer both sides first (cheap B&Q brickwork sealer works too), we're talking clear patio type sealers here, not varnishes.
Fitting the vinyl - Either template the vinyl off the units if you know how, or ask a floorer to show you quickly how to use a hooked Stanley blade on it, to give a properly chamfered edge against any fixed plinths or skirting boards. Yhis is a very slight chamfered overcut that slightly lips up the unit, so that water and muck doesn't get behind it. Vinyl must be stuck all over before cutting it in like this (Ball's F44 or equiv. + notched trowel)... and work in warm conditions or use a hot air-gun/hair-dryer at the edges (on low!) before cutting in. The force required on the hooked blade is high, see H&S, use both hands on knife and once hooked into a V'eed corner to start, the knife is used to force the vinyl into the floor/skirt corner, the blade being bent (twisted) so that the hook runs along parrallel to the skirt with knuckles just skimming vinyl (else Altro will take all the skin off!)
If you don't chamfer it properly with a hooked blade, then definitely use a flooring sealer around the edges, esp. at the sliding door, where there should be a hardwood timber or metal edge to accurately butt up to. Just covering it with a door-plate won't in itself stop water ingress.
Superb floor for a camper, carpets won't slip on it easily either... could rough it out (Vee'ing the corners), stick it down and drive round to the nearest carpet shop to find a fitter who'll cut it in properly for you.
Materials - Altro and cheaper copies come in different ranges and thicknesses e.g. 2, 2.5, 3.0, 3.5 & 4.0 mm
2 or 2.5 mm will be just fine and much easier to work with!
H&S. DON'T use retractable blade OR break-off blade knives, nor an old sloppy fit one - the original Stanley style cheap fixed blade ones are best, with a single clamping screw (£4). If using straight blades for any trim work, get a pack of HD 1992 Stanley blades, not the thin 1991s that usually come with them, intended more for modelling than carpet or vinyl. Proper Stanley blades have the number stamped on every one. Or ask a tame carpet fitter for a 'pack of five' - £1 should cover it.
Hooked or straight blades and lots of force can jag knees, arms and even arteries badly if the knife runs away with itself - never cut with force towards you, or use it to slash cut with. Left to right for a right-hander, using BOTH hands on knife is the norm for floor work, esp. for cutting vinyl.