This is what Sue and I did just before Moab last year. She sent a spare unit to the fix place, they fixed it and sent it overnight to me, I had my mechanic do the swap, then I sent my broken one back to her to keep as a spare. Worked great but as you say it relies on trust. What I don't think anyone needs to worry about is the repair place; they fixed the problem and had it shipped to me right away!