My take is a IBT at the 'trailer', as that is where the cable, telco, dish, & etc. guys install the various demarcs.
'Trailers' are hard wired, wheels off, anchored, skirted. Electrical service is independent for each, POCO meter, 100 amp disco at the pole, and 4 wire feeder (PVC/THWN) to the installed panel. Grd rod, IBT, bond to frame.
