Help installing radio in golf cart?

I am attempting to install a radio in a golf cart we use at our camp for kids with disabilities. The golf cart runs on six 6 volt batteries so I have installed one 12 volt battery in the back to operate 12 volt accessories. I’m not sure how to properly ground the 12 volt accessories. Can I run a line from all the 12 volt accessories to the negative terminal of the 12 volt battery? or, can I ground the negative terminal of the 12 volt battery to the frame of the golf cart and ground all the accessories to the frame? Any special tricks to grounding the radio antennae? Sure would appreciate any good advice. Thanks

You may connect the 12V(-) to the cart chassis but be careful not to connect the 12V(+) to the 6V(+).

You can use the chassis as ground for the accessories but make sure not to mix the 6V(+) and the 12V(+).