X6 battery strap

[tjf]

Hi all

Recently bought a used X6 and I want to run a normal 6 cell pack across the middle till I get a chance to sort my cells. Now the strap seems mega tight to fit cause the outer cells sit higher as they are not recessed into the chassis. Now I've had a look about and there seems to be a few strap mods but nothing conclusive for this problem.
Anyone got any ideas?

Thanks
TJF