Good stats there. That sure is a bundle of gas money but it's smiles for miles and that was an epic trip! I hope to join you all at LCDC one year.
My towing MPG is elastic depending on speed and environmental. I find myself driving faster and faster these days with the trailer, CAs towing 55mph speed limit be damned. Especially with 35s making the speedometer read 5mph low. Corrected, I'm driving around 68-75mph. I've also seen tanks in the 7MPG range but that would be the low end exception for my setup, when in winds. Looking at my last trip which was a lot of grades in the sierras and 100* degree+, I saw a corrected MPG between 8-11MPG range. I was surprised at the higher 11MPGs and that was done mostly at 4k+ elevation. Seems like air density impacts to engine output and aero drag helped that tank.