[Advanced Design]

Scott, while I haven't checked yards around here I am going to guess 15 inch wheels 5 x 4 3/4 bolt pattern are pretty rare as those wheels haven't been used in production for a long time. I needed one wheel for a shop roller and I didn't want to fool around trying to find one somewhere, so I ordered a new ralley wheel from Jegs...$60, no fuss, here in 2 days.

For your wheel tub...I guess measure the trailer fenders to see what fits the best. For your crossmember mount reuse the existing flange (or make one) and plug weld to side of trailer fender. Of course your cross sill will need shortening the matching amount.

Or carefully slice the bed side out, move it in the needed amount and fill the gap with 19 gauge.

TCI chassis...cool! Must be a new acquisition?