By the way, 18gi (eg, 22T-32T) is entirely rideable provided the user is predisposed to a higher-than-mashing cadence.

The OP could easily invest in, say, an Ultegra triple lever set which can be used as a double, and do the compact crank thing. If he then decides that isn't what is required, he can continue on to a triple.

The thing about using larger cassettes is that there is a need to use an MTB derailleur.

As randonneurs and touring cyclists, we have been through this whole process. Machka's bikes have been equipped with MTB cranks (26-36-48) and 11-34 cassettes. My current go-to bike is equipped with Ultegra triple with 11-32 cassette. Both have XT derailleurs.

My touring bike used, for a long time, a 22-32-44 crankset to 11-32 cassette, but now runs a 26-36-48 crankset. I have a 22T chainring to go on it if I am heading to really steep country with a touring load on board.

I've ridden most of my time in hilly terrain, and I have perfectly good knees that I want to keep that way (although I do enjoy riding fixed gear). I honestly cannot see how the OP could entertain riding something like a 34 compact to a 28 cog in 8-12% grades without threatening damage to knees that he already considers at risk.