it’s easy to control the Mastervolt alternator with external Alpha pro regulator using a Victron Battery-protect (the smallest), in position 7 it is used as a control relay by the Victron Ve-bms. The consumption is 1.5 mA completely compatible with the maximum authorized current of 10 mA of the Ve-bms. A second, ordinary relay, powered by the ignition key, will only activate it when the engine is running (+ a manual switch for security). The bluetooth version of this Battery Protect allows you to control the charge with a smartphone (stop and start). When I sail with the engine, as soon as the voltage of the batteries reaches 27.6 v (95-98% of charge) I stop the alternator with the smartphone so as not to keep the batteries at a high voltage for too long (the duration of absorption of 28.5 v is 4 h with the Alpha pro). For the other loads, if they are Victrons they can be managed by the Ve-bms otherwise either they have a remote control and another small BP will be used or there is none and a Battery protect of suitable power can be put on the charging cables. Note that the Ve-bms has a maximum control of 10 mA for the charge and 2 amps for the load (+ 50 mA for the pre-discharge alarm). A bluetooth BMV with audible alarm informs as soon as the voltage is high or low (adjustable). The smartphone will check each battery cell and you can stop the charge or the load if necessary.
For the battery charger, if you are in the boat, you can drive it yourself with the bmv and stop it as soon as the charge is finished.