What size are your current clamps? Here's the sizes for the Red Tops terminals. You may just have to fit a new cable which isn't difficult, either that or cut yours, unsheath the wire and use this
Ah the actual clamp that stops the battery moving? Just get some smaller threaded rods, or raise the battery up on something. I've never had mine clamped down and it's never been a problem but then it is huge and weighs a ton so it's unlikely to go anywhere
Are the red tops smaller than the yellow tops ? I have a yellow in mine and there is no room for a clamp as it sits so high. See image below and you can see the screwed rod just proud of the battery top. Mine isn’t clamped down and doesn’t move.
That's a lot of wiring :|
Just as well as I found today I can start the vehicle with the heated rear window switch 
