Chris
i am sure that some of the technical wizz kids can give you the answer you request.
But meanwhile I am going to give you the answer you dont seem to want - you will get much more out of this in the long run if you work on playing rather than a technical solution. And it will not take 10 years. Most people can make decent music using an arranger within a few months, not years. That is really the whole point and popularity of arrangers, they make playing much easier. Find someone to give you lessons, and you will be there faster than you think. Or use an online system of learning.
You can also easily start by just recording the lh chords using fast record, do it at very slow speed if you are struggling. Then play along using the rh at your chosen speed. Yes you will have an initial investment in time to learn how to play, read, change chords with your LH , but not at the same time as you play RH. And many, many songs use only about 4 chords, and in the key of C that is not really hard to learn - an hour a day for a week and you will be there.
Think of it like this, lets say you want to learn to play golf, but find it a bit hard, would you then just let someone else hit all the long shots and just learn to putt? Would that be any real fun??
I am sure you bought the keyboard to learn to play, dont give that up, invest few months, and you might surprise yourself.
Cheers
Mike