You could always get one of those job box fuel tanks and have it modified to tap into existing tank, if you know someone who knows how to do it. Would cost you more $$$, but it;s an alternative.
Thanks. I have seen those and other "in the bed" fuel tank options but I really don't want to do that. I "Googled" auxiliary fuel tanks before I posted on here and all I could find were in the bed tank options. I was really looking for an under the truck solution. Back in the days of my youth (25 years ago) my old man had a full sized Chevy and there was a switch on the dash where he could select between 2 tanks. I don't really recall how large they were but seems like 20 gallons or more each. Anyway the range on that truck was unreal.
We tow a 5th wheel toy hauler and I'd rather not consume the bed of the truck with a gas tank. The only thing I'm worried about is remote areas in NY, VT and Canada. Diesel can be hard to find in those areas. I can't believe Chevy doesn't have an optional solution for this. If I can't find an under the truck solution I'll probably just buy 2 - 5 gallon diesel cans to take with me when I tow to remote areas. That way I at least will have 110 - 120 miles of padding if I start to run out.
I find the guys on this board to be highly knowledgable so if no one on here knows of a solution . . . I doubt there is one.
08 Silverado 2500 HD 4x4 w/ Dmax - bone stock because I just got it . . .
05 Chevy Caviler
02 Pontiac Trans Am WS6, Hurst 6sp, white w/ blk leather
02 Pontiac Grand Am GT w/ ram air
03 Yamaha FJR 1300
05 Polaris 700 XCSP w/ M10 and the works
02 Polaris 700 XCSP w/M10 and the works
05 Polaris 700 Sportman
04 Rockwood 31' 5th wheel w/ slide out