IMHO, I wouldn't even consider anything but diesel to haul 13,000+ and yes, it WILL end up being +. There is no sense cutting the GWs too close. A gasser might fit into the parameters for your truck, but why cut it too close.
You get what you pay for in a truck. This why they build diesel trucks to begin with. Just my personal opinion from my personal experience. I'm sure others will have their opinions also.
Oh, and by the way, welcome to the forum. Lots of good folks with plenty of experience to help you whatever the need.
2013 Silverado 2500 HD Duramax/Allison Tuned
Aviator Wright Flyer #1919
"First In, Last Out". 11B4Y
DAV, MOPH, VFW, 5/7 Cav,1/8 Cav Assoc.
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