Size of ledger for Kohler Villager cast iron tub?

I'm installing a cast iron tub and am wondering about the thickness of the ledger. The lip of the tub that rests on it is very narrow. I think that the curvature of the tub would interfere with the thickness of a 2X4. Any suggestions for what size to use?

Also, my tub has feet that it rests on. The ledger board is really for extra support, but the weight of the tub rests more on its feet and not so much on the ledger? Is that right? The tub's instruction manual advises against the use of the ledger, but I've heard otherwise from many people.

Any tips you have would be welcome. Thanks.

Oh yeah, and I was wondering about metal shims? The manual recommends the use of metal shims under its cast iron feet. Home Deopt doesn't carry them. Anyone know where i could buy metal shims in the Seattle area (Bothell)?

I've installed dozens of the Villager tub using a 2x4 ledger and shimming the apron to keep it from rocking.
Find the high point on the floor where the apron will touch, mark how how the ledger should be from that point, then draw a line with a 4 foot level around toward the back. When you set the tub, there may be a gap at the lower part of the floor under the apron. This is where the shim goes.

Installing a cast iron tub

Thank you. And one more question. Does the tub just rest on the ledger? It doesn't get nailed or attached to the studs in any way? I don't see any nail holes or anything like that in the nailing flange. Thanks again.

Thank you. Should I use metal shims under the feet or can I use a composite shim? If metal, do you know where to buy some? Thanks again.

You can pin the ledger with galv nails, roofing nails work.
I have never used a shim under the legs. and I don't think hj has either.

Either chamfer the edge of the 2x4 to relieve it where the curvature meets it, or use a 1x4 which will give all the support you need. Use metal bolt washers for shimming if you need it.