ex horse float insulation

have just bought a S/H metal skin horse float to be converted into a mobile shop for street markets etc. We are into laser cutting stuff.
my Q is about insulation .. There will be a large roof vent (same as caravans have)and during markets one side will open up completely, so insulation concerns not as important, but more so when at home and stock that would be left inside float/shop, as its metal skin with internal ribs about 50mm square would there be any benefit in applying spray on foam then a sheet of MDF/ply over the foam screwed to the ribs.
or other left field ideas.

FWIW ...

my suggestion would be to use some sort of fibre batting insulation rather than spray foam.
Definitely line the inside of the horse float with 1/2" (or 3/8") ply -- gives you something to drive screws or nails into.

The open side will need some specially designed reinforcement as the rigidity of the whole structure comes from it's construction as a box open only at one end.
Opening up one side will destroy that rigidity.

will the side open up to become a ramped floor or an awning? If the latter you will need to provide some form of step between the floor of the trailer and the ground.

Thanks Ian,
this float is different shape to most Ive looked at.....

Attachment 466178

Attachment 466179
This is way out of scale but gives an idea of whats planned
There will be hopefully 2 caravan style air vents in roof. the side that opens will have plenty of extra metal (welded) bracing, in addition a Caravan awning will run the full length and pull out to give shade.At each end metal frame panels will drop vertically into place acting as wings and give even more hanging display area.

Eventually a small laser engraver will be added so we can custom engrave names etc on luggage tags, key rings, and other bits n pieces.

Most stalls are hired as 3 x 3m and as this will be about 4.5 total, will set up next to mate who put me onto this idea as he runs 2 horse float coffee shops, so we can then rent 3 sites for 2 outlets, rent power off his genset and his aroma to attract even more business.

thats the plan anyway,