I'm in the camp that as long as you're mostly level, then it shouldn't be a problem. If you're in a spot that is not very level and if you can control them manually, perhaps you could put them down just enough to take out most of the movement, without necessarily leveling the motorhome.
Along those lines, though....
That said, I've taken a bit of a more cautious approach to our overnight parking. I rarely put the jacks down anyway. I know you're towing on a dolly, so this probably isn't relevant for your situation, but I used to put our Honda Odyssey in "Park" when we arrived at the spot. (Honda's of our era can be towed four-down and require a shift through the gears, leave in neutral for 3 minute procedure before towing, repeating every 8 hours or so.) We've never had an incident and the areas we have chosen have apparently been pretty safe (commonly, Walmart's, occasionally Flying J's & Rest Areas). BUT...I keep hearing stories about RV'ers having overnight security issues which got me thinking. If our Odyssey is in "Park", and the jacks are down, I can't just turn the ignition switch and GO! I'd have to get out of the RV to get the car ready, while also taking the time to raise the jacks. This could easily take 5 minutes or more, and puts me OUTSIDE the moho.
So NOW what I do is keep the jacks up and when we arrive at our spot, I run the minivan through it's "pre-tow procedure", leave it in neutral, and then lock the minivan up with our other key. It's ready to tow if NEED be.
With this method, IF we see or hear something we don't like, I can just slip behind the wheel, open the front curtain, start it up and roll on outta there until we get someplace which seems safer.
Is that all necessary? Probably not, but it does add a bit of a feeling of security when we have to park overnight in a strange area. Don't get me wrong, it's not something we lose sleep over, either. By the way, we usually feel most secure at Walmarts and usually do some morning "breakfast shopping" when we pull in and pick up any other supplies we might need.
Safe Travels!
~Rick
2005 Georgie Boy Cruise Master 3625 DS on a Workhorse W-22
Rick, Gail, 1 girl (27-Angel since 2008), 1 girl (22), 2 boys (23 & 20).
2001 Honda Odyssey, Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.