"Real" Weight of 3124

We are shopping for a used 3124, KS preferably, and will also be buying a tow vehicle. My questions are: 1) what is the actual weight of a 3124 without personal effects, which I can tally up, and 2) how close to real will the "only 1 gal of gas/100miles" be on my mileage. I know individual vehicle has a strong bearing but an Elkmont will force you down to 10mpg towing. What would a 3124 mpg loss look like by comparison? My quandry is I don't if, for example, a Ford Flex is OK or do I need the higher rated (and lower mpg) Explorer.

Thanks in advance and we looked forward to joining you all soon as TM owners.

Jim in Michigan