I have NEVER seen a statement in any Furnace Manual to NOT operate furnace while in motion.
There are warnings about blocking/obstructing air flows.......out and/or in.
'WILDTOAD'
Which Suburban Furnace Model/Manual and what was actual statement??
If floor registers are blocked due to slideouts etc then furnace may overheat due to lack of proper discharge air flow thru heat exchanger.
If return air is blocked then furnace may overheat due to lack of adequate air back into heat exchanger.
Overheating will cause furnace to trip on 'high temp limit' switch.
Then it will cool down..refire.....over heat....trip repeat cause t-stat set point has not been satisfied.
But if nothing is blocking/obstructing air flow......run it.
We do when traveling in cold temps and our rig is a 5vr. Still nice to walk into a warm unit when setting up in cold weather.