@Bosley Open the YE box, on the inside of the cover is the electrical diagram. Your YE board should have a 120V Direct output at A0 (top right). Pin1 (black) should be live, Pin4 (green) should be ground. If the 4-pin A0 output connector doesn't exist, the equivalent should be: P1 = P32 (black / line, 15A fused, located top right of the F2 fuse), P2 is blank, P3 white/common depends if your spa is wired for 120V or 240V, if 120V then it's P56, if 240V then it's P67, and finally P4 = P47 (green / ground). Read your actual diagram and test with a multimeter to make sure.
If you treat the drape-over Saltron as a 120V auxilliary component, wire it in securely using a Gecko PP1 connector and the built-in rubber waterproof wire covers, you should not void warranty on the YE pack. Since Saltrons are drape-overs and not plumbed in, your spa warranty should not be affected either.
You will likely void the warranty of the Saltron because you have to convert it from a wallplug to Gecko PP1, although careful disassembly of the Saltron could allow you to reconnect the original power cable later if needed.
I'll note that with -20C and colder temperatures, the drapeover introduces a gap that lets cold air in. I don't use a drapeover SWCG for that reason, I prefer to keep the heat in as much as possible. If I was in a warmer climate, I would definitely use a drapeover SWCG to maintain a baseline level of chlorine at all times.