I did a 30 mile road test of my Weekender-XL today, with a visit to the scales. The inside is unfinished, so I still have the foam board and 1/16" paneling to install, a single bed, counter and some storage, plus the sundry lights and 12v-115 vac power.
My HHR pulled it just fine. The mpg readout was showing 15mpg to 25mpg. It's very sensitive to a little bit of grade, due to my 2.2L engine. I think 17-18mpg is going to be the best I can hope for. My 2014 Dodge minvan with the 3.8L engine and 6 speed would be a better tow vehicle. I think it would average 22mpg- about 5mpg less than normal.
I'll entertain some guesses now as to my empty weight--

Its a HF 1195lb chassis, 3/8" plywood skin, 1/2" plywood floor. I stretched the frame 6" in front of the axle= 102" long trailer, w/ a 60/40 distribution. measurements= outside is 127" long, outside width is 68" and the inside ceiling height is 61.5"
It pulled easily with no surprises. I expect it to do OK with another 200lbs added to complete the camper- as long as I monitor the tongue weight. It came out to almost exactly a 15% hitch weight. I feel that I met the weight goals for my extra large Weekender inspired design.
leaving the scales-
back home,