Welcome to the Forum from Western New York State!
Unless someone here happens to have one, finding one from Jayco might be a stretch, since they purge information after a few years. Your 2007 is at 16 years old. It's a long shot at best but give them a call or email with your year, model, and especially the VIN number and keep your fingers crossed.
On the ground, the white ground battery cable should run from the battery into a metal junction box on the frame. Original boxes aren't waterproof, and may have allowed corrosion on the wires. Originally, they were tied together in there with household style wire nuts, which lends itself to corrosion and bad connections after a while. The end result may be some detective work on your part with a digital volt/ohm meter, which is a good idea to have anyway. Good luck, and let us know how you make out with it.
If you're going to "regret it in the morning", sleep until noon.
2012 Jay Flight 19RD
2016 Ford F150 XLT 2X4 SC 3.5L Eco Max Tow
2010 Tundra TRD DBL Cab (Traded)
2 new fluffy Corgis, Bayley and Stanley