Room rearrangement. Cable question

Kolledog, it depends on the impedance of your loudspeakers. If your speakers are 4 ohms or less you are probably better off with shorter speaker wires even though your system is not balanced. I always ran long unbalanced interconnects to mono amps behind the speakers and never had any trouble. I would use a cable like Canare DA 206 which has twisted pair inner conductors of heavier gauge then you attach the shield on the preamp side only.
If your speakers are 8 ohms or higher longer speaker cables will work fine as long as you keep the gauge low enough. I would say 12 or lower. I like Kimber Kable either 8 or 12 TC. 

Long speaker wire since you can't do balanced which is much better.

I have one of my four systems setup that way, equipment on the side with 20 foot speaker cables.  System sounds great with either of my two tube amps or my one class D amp.  The cables I use are DH labs Q10 in biwired configuration.

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.

I have the same issue. I am going with a very low equipment rack in the center of the room. Low enough to avoid most reflection, but not necessitating other expensive changes.

Here's an example of a low table but it could have two shelves: https://hauteliving.imgix.net/product-photos/low-lessness-coffee-table/low-lessness.jpg?auto=compres...