60 should be good, PW. Slow and steady. Our 1400 mile OW on I5S in 2-34's pulling FB trailers found us doing ~60 all the way. Slow and steady wins the race. Inspect the trailer tires before you leave. We had one blow out on the FW, was reimbursed. No huge deal, but it did set us back a few hours.
Nobody puts baby in a corner. 60mph.
