Bought an old but sturdy boat trailer for $125.  After staring at it for several hours this is how it got modified.  Took off the old rollers.  Built the wood frame.  Bolted it to the trailer frame on the rear.  Used U-bolts everywhere else to secure it.

I have UHMW strips coming to attach to the wood for easier loading and unloading.  I found a company nearby who builds dump truck bed liners out of UHMW and they gave me a good deal on their cut off's.

RonB