Are a trim limit switch and trim gauge switch interchangeable? My limit switch went out, the gauge switch still works, and I don’t have time before my lake trip this weekend for a proper fix of removing the lower unit and am wondering if I can swap them out and just splice the wire for them together for the weekend. I'd prefer to have the limit switch working and just drive the boat off of feel. I’ll fix everything up correctly when time permits.

I *believe* that the guage switch uses a resistor and the lilit switch is open/closed, so no. The guage is more important so you lucked out there. Back by the pump are the bullet connectors for the limit switch and you can just tie those together and have functional trim. Just keep an eye on your guage and limit them yourself. That'll keep you on the water at least. Buy Mercury switches when it comes time. The Sierra units are junk.