Overcoming a handicap, need suggestions from experienced players

[Garquillex]

My right-hand index/middle are unnaturally fast. Me left-hand (all of it) is... not very good. And it also suffers from chronic pain just under the knuckles. It only hurts after some fatigue, so I want to keep that fatigue low while playing competitively 2-handed.

That means I want to take pressure off my left hand and add it to my much more capable right hand. Being an on-and-off player for 3 years, I have always stuck with the 1 hand 3 index method. Sure, it might fit me pretty well, but I no longer want to stick with it. Now I need to find a hybrid-spread method to accommodate my respective abilities. I don't think I can do that on my own though. I'm not familiar with the higher-end playing to the point where I can gauge the best options. Hell, the best I've done is almost FC'ing Raindrops, missing 3 all the way at the very end of that speedy chain at the end of the song.

I'm considering looking into split arrows/diagonal arrows. I read somewhere that it essentially takes some 2-handed trills and makes them one-handed, which is normally a problem for spread players, but is good for me since my 2 fingers can tap faster than the fastest trills. And in respect to that I want to setup a format that can let me choose different keys for different situations, which is only doable with both the in-game keymapping and the program for keymapping, which means there would be duplicates of most keys on the keyboard surrounding KL or whatever other 2 keys my right hand uses. I think this may be taking things too far, but it seems that it is evened out by the added complexity of managing 5-9 keys instead of 4. Edit: Extra keymapping has been cleared up as cheating.

Tell me what you think about the split arrows.