Ok, slight update, and I think I have a plan now. I checked and was told that there would be a Fender Hot Rod Deluxe or a Peavey Classic 50 available as a backline amp. I'm sure I'd be fine with either, but would welcome your opinions on which of those you'd prefer as well. I suspect I'll lean toward the Peavey. I'm going to tell the other guitarist that if he wants to bring his amp and have me play it I'm happy to, I'll haul it from his truck to the stage and back, but I'm planning to just play a backline amp unless he really wants me to play his. I wasn't sure what they'd have and worried it would be something barely adequate. I'll probably also bring a cheap "emergency" amp along just in case.