As long as we're dealing with hypotheticals, if you could get to Houston, Texas area, there are several members here that you might be able to ride with....
I have a CCLB and a Burb,(both should be running by this hypothetical timeframe)and several local members have at least one truck. Also, if you have a general GM truck meet, there are several SE Texas/Houston area members of the square body forums too, that probably wouldn't mind an invite.
And if you had a GM truck meet that had a cutoff of 2007 classic and older(GMT 800/NBS) ... it seems to be mostly the later models that are the bro dozers/pimped out/squatting rigs that "real truck" people don't care for, so that would take care of that issue.
Some more things to consider....I like the fairgrounds idea; they're usually decent places to have a car/truck event. I've been to many swap meets and car shows, most of my life, and the majority have been at fairgrounds or other county facilities. Another thing I would add, is if we have a swap meet and/or vendor area at our show, it would be great if there's a covered area for this. Doesn't have to be a closed building, a pole barn or open pavilion works.
At the Lone Star Roundup, the big custom and hot rod show in Austin every spring, the host clubs hold it at the county rodeo arena and grounds, northeast of town. They have a big stock barn that the swap meet is in, and vendors row outside. Those who want to be outside, bring tents and such, but it's nice to not have to be outside if you don't want to be (or have merchandise that is weather sensitive like toys or clothing).