How do you adjust the legs for support and levelling? Can you reach with the walls in place? Or do you need to go back and forth? Tub in - check - out - adjust - back in check - adjust - etc.
This might help you answer your own question.
You might check the area first and see which side is high. If for example you plan to leave the left side open this would free up both levelling legs there. This would be easier than lifting that heavy beast back in and out for fine tuning.
Good Luck.
If I install the tub as I was originally thinking I wouldn't put up the third wall until I had the tub installed. This third wall will include the plumbing fixtures. I intend to make sure the subfloor is flat and put steel plate - or something similar - where the four feet will rest. I know getting 4 points exactly flat from the get go is near impossible but I'll have fairly easy access to 3 of the legs so shimming in place shouldn't be too difficult.
I get how the ledger board makes for a simpler and more stable install but it conflicts with the manufacturer's warning. I know some of you don't think this warning is worth the paper it is written on but I have a hard time reconciling that with the manufacturers expressed concern. They must know something about the product they manufacturer. I guess if I had a better understanding for why they have this warning, I could get more comfortable with the ledger board approach. Is it because the tub rim is not strong enough to support the weight or is it concern about how the framing and ledger board is installed?
I've been thinking that an alternative approach is to use ledger board but put each leg in a small pan of mortar. When the mortar sets up, the weight will largely be born by the legs with the ledger board fixing it in place relative to the tile. Does this make sense or am I missing something?
Louis