I have a "bought " one in SS. It has a frame loop at the front to stop it sliding forward. Quite thin walled At the back , it uses nylon straps with the snap-together type catch to stop them sliding backward. Sliding backwards is actually the main thing you have to guard against while travelling--DAMHIK. I'd put some Octogrip or Z-tread on the chequerplate to protect the bottom of the fridge. It should still stick down, particularly if you use the 3M primer 94 as recommended. Best purchased from this mob , https://www.formasign.com.au/product...d-whole-sheet/ full sheet, much cheaper than buying overpriced bits from Whitworths. Or have you considered using fridge slides? would need to be all stainless.
Your main problem with that single lid type of fridge is going to be having to slide them all the way out to get the lid open. PITA. Hence the suggestion of fridge slides. I wanted to keep it simple in that respect, and not have a fridge rust away, so I built my own with split lids. All fibreglass and ali . But quite a project. Since the pic was taken, I have re-done the lid split to make it 50/50, easier access without having to move the fridge at all, in most cases. And put z-tread all over the deck. The black nylon strap loops through the lifting handle before clipping together, to stop it dropping down.
EDIT---just went out and measured it. The od is about 31.7mm, and the wall thickness( measured) is 2.11mm. Looking at the Bluescope shedule, this doesn't really fit in anywhere, it's too large an OD for 2.11mm wall thickness in either 304 or 316 tube, and the Ornamental SS tube is thinner walled at that OD. If you wanted to go ali, you'd need 32 x 3mm to be sure of taking the weight, particularly as you would be spanning a greater length with that kind of design.