It is possible to modify the steering wheel clock spring so you still have a working horn button and turn signal cancel. In my case, I’m using an NRG short hub and NRG Quick Release 3.0 along with a Sparco steering wheel. The horn button was salvaged out of an old BMW 2002.
Assuming that you’re not going back to a stock wheel with airbag any time soon, you just need to grind back the connectors, leaving the two pins circled in the photo for the horn. Use a continuity tester to figure out which is ground and hook up your connectors on the Quick Release hub. Then hook the horn button to the wheel half of the QR and you’re all set.
For a more detailed write up of how to do this yourself, see this post from 2017. The parts on the E46 M3 and the R53 MINI are almost identical.