Pick the layout out of your new batteries and order custom length and gauge wires. They’re aer places online, and they deliver in about a week.. Going from 6 6V golf cart batteries to six BattleBorn (or whatever brand) will free up a lot of cable space. Not to mention that 3 lithium 100’s supplies about 8hrs more draw/run time as 4 of what you have now.
Make sure you measure the height width and length of what you have now! Your battery tray is welded to size. I have heard tales of folks who failed to measure and barrel their way through with torches, hacksaws, etc. to make do. Don’t be that guy.