FMCA says they list only those vehicles whose manufacturer says are flat towable. In other words, you "Should" be able to find a page in the Owner's Manual that says flat towing is OK. Maybe with conditions, but OK.
That said, I'd want to see the factory owner's manual and satisfy myself that the manufacturer said flat towing was OK.
REMCO, purveyor of lube pumps, is another source that is usually correct. Still, Show Me the Manual!