Hi Bryan,
to FiberglassRV, we're glad you're here
Lots of kind and helpful people here on the forum and lots of good info in the archives.
Simple... usually goes hand-in-hand with temporary. Whatever you do, DON'T glob silicone around the outside on the exterior. THAT is a temporary solution that can turn into a permanent problem. Since winter isn't far off, and if Bob's idea doesn't fix the problem, perhaps you'd want to remove the A/C unit and fix it so it lasts leak-free for years.