Thanks for the feedback, everyone!
Just back from Telluride Bluegrass Fest where we used this rig to keep about 30 cell phones charged all week, to light the party/picking tent every night and to run a coffee grinder in the mornings. In full sun, the 85 watt panel fully charged the batteries by noon, which was amazing.
To answer Ian's question, I ordered the solar panel from UL Solar in Las Vegas. They sell them on eBay but I ordered the same panel for the same price off their website, and also ordered a 30-ft pair of MC4 cables so I could have flexibility in positioning the panels in the sometimes shady campground.
The Kyocera panel to which H2O posted a link is priced at $425. UL Solar's 85watt panel was $195, including shipping. There's probably an efficiency difference between the brand name panel and the no name Chinese stuff, but it worked well for me last week. The 30-ft MC4 cables ran me another $40 or so.
http://www.ul-solar.com/Ian, can you recommend a more efficient inverter? The one I'm using is standard crap from the Pep Boys, so I know it's creating some drain by itself. Had no idea I could find one that's more efficient, but I'd like to do that.
For Kleiner Rainer, thanks for the safety suggestions. The whole rig was covered with a tarp all week to prevent it from getting wet. But covering the terminals sounds pretty necessary. Thankfully we didn't have any shorts last week and very little moisture (until we woke up in a inch of snow Monday morning!). Would gaffers tape do the trick or should I be using something more substantial to cover those terminals? Also, where would you insert a fuse in line and what amperage fuse should I be using? I wanna get this rig totally dialed in. I'll research the Anderson power pole connectors for sure.
And thanks for the suggestion about connecting the positive clamp to one battery and the negative to another. D'Oh - I shoulda figured that out myself.
Really appreciate the input, folks. Happy taping this summer!
Bevin