Tractor + Trailer Length

There is absolutely no overall length limit on the “national network” I.e. STAA routes. Look up what those routes are. No annual permit required.

 

......but there is a trailer wheelbase limit which makes most 53 ft spread axles a score for overzealous brown nosing revenue cops.

 

That is what really limits you on a 53' open deck. You've got to run the axles so far forward, the rear 8' or so is almost useless for much weight at all.