Picking up some hints and tips as I go along here.
First is that shooting an IDPA match at the relatively short distances they use, you are probably best served with Iron sights. This allows you to get on target rapidly and with a low sight line elevation, will hit where you're aiming. Second best is a red dot although these are generally higher up above the barrel. You need to either adjust it to hit the dot at 10-15 yards or set it for 25-35 and remember that at close range you need to aim high, that is put the dot at the top of the head to get a center of head hit. Third, a scope is a waste of time. Your field of view is too small to get from one target to the next without getting lost. It also will trnd to hit low if you zero it to any reasonable range.
Shooting around barricades while maintaining cover requires switching from a right hand hold to a left hand hold quickly and smoothly. For me the switch involves first moving the stock from right to left shoulder, then moving the right hand to the fore grip, then moving the left hand to the trigger. Don't forget to switch eyes too. Going back is the reverse. YMMV but whatever you use, you need to practice it until it's automatic.
Having one hand in a cast is not a common disability, but... incorporating the slide hold/release lever from their pistols to their carbines couldn't have been that difficult a job for the folks at Hi Point now could it?