Reliability is a high priority, suggest a Victron Smart Solar controller, a 100/ 30, 100/50, or150/35, although a 100/30 would be enough to avoid running at near full capacity perhaps the 100/50 with the panels in series or parallel.
Alternator to house battery, suggest a Victron Orion tri smart 12 12 30. This will load your alternator at about 35 amps, I suspect you have a small power unit 30 to 50 HP so the alternator won't be too heavily loaded.
Maintaining the starter AGM should not normally be needed, however if this is a requirement then a DC to DC converter input from the house battery, output starter battery, manually switch on for say 24 hours. Set the output to 13.8 volts. Suggest Victron 12 12 9 amp.
There are other techniques to provide a maintaining charge to the starter battery, the simple technique of connecting the house and starter battery in parallel with a manually activated switch for a number of hours is one method. If you have an inverter providing AC then a small AC charger could maintain the starter battery.
Your earlier post asked about 48 volt batteries, propulsion, and 3000 watt inverter. How does this interface to the system under discussion?
Mike