Shunt “Battery Minus” DIRECT to the Minus of the leisure Battery (as close as possible),
Shunt “Load Minus” to your Minus Busbar!
(see attached scheme)
Note: the Cable-Dimensions and your fuse-sizing could be a bit to “sporty”
60 amps for 16mm² is ok, but 175 amps for 25mm² needs to be questioned!
(as far, as you really just have the 2x 60 amps connections, there will not be any trouble, but…) for 25mm² i would not go to more than 100A
have fun!