Visited a few places today looking for ideas. At Fastenal I came up with these two possible solutions. Bolt these on, one on each side, through frame rail of trailer. Then use chain same set up as M101a pictured above
Speski OffRoad LTD, Cargo Solutions for Toyota 4x4's http://www.SpeskiOffRoad.com
"80 series, with a fridge"
1976 FJ40, Project with little progress.
2004 Starcraft 10RT