your Shamrock is an ultra-light trailer with an ultra-light frame.
these are not built the same as 5th wheel or MH frames or non-ultralight TT's.
the only way for your Shamrock to carry that amount of bouncing/flexing weight, is to have a receiver welded and braced to the frame.
BUT this mod will void the frame's warranty unless your Shamrock's has expired. if so, go for it.
be aware, since TT's/HTT's don't have shocks, the load of bikes will be bouncing up/down and back, putting forces that can cause most bike racks to fail.
very few rack manufacturers will warrantee a rack for RV usage. Swagman is one of the few.
bottom line is that 5 bikes will be extremely challenging for any bike rack, let alone one attached to the rear of a trailer.
my suggestion is to get a roof rack system from Yakima or Thule, for your SUV. 5 bikes is just too much weight for any other type of setup.
