Originally Posted by
Schlafen
i would try a 40t cassette without a road link first. If he needs one, derailleur hanger extenders are available everywhere in the world for about a 5'er. eBay, amazon, etc.
A generic derailleur hanger extender could well work with his existing RD, and might be available in the OP's area. It would also very likely work with the upgraded RD and shifters you suggest.
Might be worth a try - with his existing FD first without, then with the derailleur hanger if necessary. But the OP would have to find and buy a 9-speed 40T cassette to try it with his existing FD, and he could end up stuck with something he can't use. Ditto with an 11 speed RD and shifters. Dunno.
OP's bike, so that's his call.