I tried that setup as well, but I found that accelerating with R2 and upshifting with R1 was awkward for my fingers.
So I came up with the idea 💡 of switching the two shift buttons, and for me, it works perfectly.
So I have L2 as my brakes, L1 as the upshift, R2 as the accelerator, R1 as the down shift. This might sound odd but it feels completely natural to me.
It means I can control the braking with one hand and not have to worry about other button presses with that hand (outside of my thumb to control direction), then with my right hand I can use the downshift button without having to use the right hand for anything else.
It separates the two functions properly and gives me more thinking room.
At least, I hope so.