Have found a prebuilt rack on Amazon - 3' X 4'. So now I will just drill thru the plastic, down along the tubing, for the rear mounts. Using 3/16" X 1-1/2" X 5" flat iron for a stiffener on the top side and with holes drilled in plate, I dropped 5/16" bolts thru these pieces to the underside along by the tubing and then then tied the two bots together with another piece of flat iron, kinda like the old muffler clamps. Risers, as required will be used to get clearance on topside over roof structure.
Back to the top side, between these two rear supports, I will span it with some 1/16 X 1 X 2" thinwall tubing and prob mig weld. A person could bolt something together is they choose. As mentioned, this is what was done for the rear., The front will be much easier cuz of the underside spacer will not require no rigging from the underside, just another piece of flatiron, stiffener with drilled 5/16" holes and a riser, 2", for req'd roof clearance. Then span the RHS and LHS, with more of this 1 X 2" tubing and fasten . When the Amazon parcel arrives, the rest will be what it is...This may not be as clear to you as i would like it to be but once I got started, it started to develop and I think it will do the job.. Nothing heavy going up there, prob just bedrolls and the like, when 3 or 4 might go to cabin on the trapline. I can see that a tub trailer might have to accompany a crew of this size..