I’ve read this thread in full and can really sympathise with you. I hope the injury heals fully, and remember you want it to heal up properly so you can enjoy that retirement rather than always looking back and wishing you had let it mend.
If I were in your shoes, I would take whatever light duties they give to you, however mind numbingly boring, and put up with it for a year then retire. If I were your manager I’d be really uncomfortable with you not taking up a relocation only a few miles further away, especially as it’s only for a year. As you say, I dont see how you could go on further sick leave if light duties have been offered that are suitable for allowing your injuries to heal, as refusal to take them on if fit to do so is almost just refusing to work.
A difficult situation for sure, but for what it’s worth, I’d ride it out for a year even if it’s a bit more distance to work and the work is boring. Plenty people who already do that anyway, probably your manager included, but they dont get to sack it off after a year.