questions on parking dp vs gas on grass

I hope this isn't too dumb a question... When I see a DP for sale, like online, is that the height they are going down the road or does the air ride raise it more? My 2005 Georgie Boy 35 gasser is parked next to my house, on a gravel pad. I back it up over my yard. Is the DP lower? The gasser is already pretty low, the jacks aren't very high off the ground. I don't think anything lower will work without having the yard recontoured. Also, can I back it over the yard? It looks like a 45 dp with tag is twice as heavy. Can you lift the coach with the tag or with the air bags without modification? Finally, my grave pad is about 4 or 5 inches deep of big 2 inch rocks. It is level, so the gasser parks there and doesn't sink, I assume a DP would be okay? I'm hoping to move in a year or so, so I don't want to put in a new concrete drive and pad.
I'd hate to buy it and not be able to park it! Every storage place I've parked I ended up with busted mirrors, scrapes, and $$ repairs. Covered storage is like $500+ a month!!! Yikes!