Balanced is for pro use where "long" is 200 to 300 METERS. 20ft is not "long". It is however long in terms of you will never buy quality speaker cables that long. You will cheap out - everyone does - and this one thing alone will erase a lot of what you hope to gain with the move.
This is no idle speculation by the way. I have heard the difference and know what I’m talking about.
Another reason not to run long speaker cables, either they will have to be different lengths (killing you even more up front and even worse on the back end when you go to sell them) or the extra coiled up somewhere.
You will find it much easier and better to just run long RCA to the amp. Then normal length speaker cable. Don’t use a rack, put the amp on Townshend Pods. Or a Platform if you like the look better. Do not just lay the interconnects on the floor, suspend them every inch of the way. Same for the speaker cables. This is how you do it.
The rack by the way, all you are doing is moving a problem from one place to another. Ditch it. Do that and more than likely you can avoid this whole off to the side issue altogether.