I had a similar problem with the K75 horn, turn signals, high beam. It took some time but I was able to get used to it and now I find it "normal." When I ride other bikes I have a problem with the turn signals. I find the BMW arrangement convenient and there is no problem with thumb movements. Practice a bit more and see if things improve. It's cheaper than replacing everything.
Horns are generally useless in this AC climate controlled, triple insulated soundproof glass, and 10 speaker surround sound system cars of today.
Best solution is to keep a big cushion, and concentrate on avoidance, not warning some clueless driver.
The above answers are not what you were looking for, but both are good, simple solutions that have worked for me.