If you want to see trailers, the place to be is Joe Nall. Hundreds and hundreds.
I just returned and from receiving many positive comments, feel this is the best way to effectively utilize the space inside your trailer.

Mine is a Wells Cargo (the best, but pricey) 6X12 single axle. I tow it easily throughout Florida and the SE with a small V6 pickup or a minivan.

I fabricate former cutouts (from the A/C plans) onto 5/8" plywood cradles, which are securily bolted (NOT SCREWED) to heavy-duty shelf brackets. The brackets are bolted and/or screwed into the steel vertical framework of the trailer.
Of course heavy padding is absolutely necessary in the cradle.
This system allows me to easily transport 4 giant warbirds (like a Meister P-47 - huge!) yet still have the floor open to walk into or place additional equipment /planes.
The wings are supported in the traditional fashion-horizontal rails across the width of the trailer.
Forget about bungee's. Not only do they weaken, they are extremely dangerous. I remember a story of one snapping back into the face of some unfortunate individual and him losing an eye. Purchased several yards of velcro and loop it through electrical conduit hangers ( cowboy clamps for those in the trade) taht get clamped onto the rails.

Good Luck,

Nick