and would like to resume instructing, but the hoops are just too many and too expensive, and the annual requirements too much
From what you say you have a valid licence and have held a FI rating, so all you need to do to instruct again is enough refreshing to pass a FI test. That will get you going for 3 years, whereupon you then only need a FI test assuming you have 100 hours instructing over the past 3 years. In the good old days you would have had to do the FI test every 25 months! Is that really too difficult if you have so much to offer?