Yes, contact Service and they can provide it. It’s real simple in just description.
Run the positive (+) harness lead for the trolling motor connection at the bow, to the (#1) battery,
then run one jumper wire from ground (-) of that battery to positive (+) of Battery #2,
next run a jumper wire from negative (-) of battery #2 to positive (+) of battery #3,
then the main ground on battery #3 has the main trolling harness ground (-) connected, which runs to the bow.
then, if your charger is inboard, each battery will have its own set of charger leads.
We like circuit breakers on all jumper wires for safety, though most companies don’t use them.