Gauging interest in a custom built all aluminum TT

Ok, I'm interested... I'll assume no slide outs? I like the idea of the welded skin - no roof membrane to weather, caulk to crack. I've had torsion axles on an equipment trailer- 10,000 lb and worked great. Smoother ride for me and the equipment. I'd be happy for axles to last 20 years.

Would you sling the plumbing and holding tanks below the floor?

All of that welding has got to take a lot more labor than the sandwich panels (wood or aluminum) used everywhere today.