You'd be really pushing it with the Lance.
I'm doing basically what you want to do, but with a 2002 Chevy DRW and a modern big block. I really don't need the DRW, but it was a deal I could not pass up.
The placard on the camper claims 16XXlbs with water and propane on board, but I'd estimate it's at least 2000lbs loaded for a trip. My tandem axle enclosed trailer's at least 4000lbs now because I just keep adding equipment, and quite heavy on the tongue.
Originally I did not tow with an extension, but I had to be careful making turns in parking lots because the rear jacks would hit the trailer. After punching a hole in the trailer skin with a jack, I upgraded my receiver to a Reese Titan 2.5" and made my own 12" extension/reducer out of a 24" Curt "weldable receiver tube."
Because the extension tube extends clear through the receiver, it is a very stable connection with little slop. It doesn't need stabilizer chains at such a short length.
I am sure would be just fine with a 2500HD or F250, though I might want a WDH for the trailer, or airbags on the truck to mitigate the squat. ~2500-3000lbs on a 3/4 ton truck does push it past level a bit.