That is a very nice looking piece of work Willy. I always admire good craftsmanship and you appear to have it.
One small thing I'd like to suggest if you'll allow me, is to mention that I see no gussets from the crossmembers to the longrail of your body. It appears to be aluminum tubing and the stress of a cars weight might very well cause cracking along the top of the longsill or up the side of the crossmember. It is considered a standard structural part on all such weldments. You may wish to consider adding them.
That in no way detracts from the really nice design and well thought out project.
I love it.