Chassis design and cost questions.

I am designing a 5'x8' tear and would like some estimates on what other builders think the chassis might cost to have it built by a professional welder. The chassis would be 2"x2" square tube in a basic square frame with 3 inner crossmembers and a straight 2 1/2"x2 1/2" drawbar. It will have a torsion axle welded to the frame 36" from the rear. It will also have 2" square plates welded into all the corners between crossmembers and side rails for bolting the subfloor through (so thats 10 plates in all). To save money I will source and install the parts for the axle, hitch, wiring, chains, leveling and tongue jacks.
Here are some specific questions I have about the design:
How much would you estimate it to cost to have this welded together? (materials and labor)
is 2"x2" square tube ok for this kind of trailer? should it be bigger?
Should I make the frame 4’10" wide so that once the side-walls are on its final dimension is 5’ wide? This would allow 5’ pieces of ply and aluminum to lay on the side-walls instead of between them for the roof and hatch.
How much space is needed between the side-wall and the axle hub? Where do I buy the axles from?
How do I attach the fenders?
Anything else I should know (or the welder should know) before proceeding?
Thanks all,
Dave
Here are some specific questions I have about the design:
How much would you estimate it to cost to have this welded together? (materials and labor)
is 2"x2" square tube ok for this kind of trailer? should it be bigger?
Should I make the frame 4’10" wide so that once the side-walls are on its final dimension is 5’ wide? This would allow 5’ pieces of ply and aluminum to lay on the side-walls instead of between them for the roof and hatch.
How much space is needed between the side-wall and the axle hub? Where do I buy the axles from?
How do I attach the fenders?
Anything else I should know (or the welder should know) before proceeding?
Thanks all,
Dave