This is all personal choice so no one answer is better than another.
Personally, I would rather drag a full 40 gallon tank once, than a 20 gallon tank 3 times. Why three? There is no way to gauge 1/2 a tank when dumping. If you try for a "full" Blue Boy, I guarantee you will miss (over) once or twice. Well once anyway. I don't know about you, but there would never again be a twice. There is no "nice" way to disconnect without a mess when the dump mast and hose are full of poo.
The pneumatic tires make pulling on soft ground easier as well. No doubt about it, dumping is a chore I hate and want it over as quickly as possible. That cold beer afterwards can't come soon enough for me.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW