safe, might be.
smart, you know.
even when my old 12v was in its worst temps(220DVs, DDP4's, ground plate, gsk, and stock turbo) my temps were resonable driving empty. i could hit 1300* in third but it never stayed there long. i would at least get an egt gauge. even towing light, wind resistance and hills add up.
all that said, id probably do it but make sure you get gauges on the way. at least its safer that way