I used to live aboard my 33 Hunter. I had a Wind Gen and one 80W and two 20W panels. The two 20W and Wind Gen were dedicated to refrigeration batteries. The 80W was to supplement the dual house/starting batteries (on a selector switch).
The best bang for the buck was a High Amp Alternator from West Marine and Battery Isolator. I found that I could keep up with the battery usage if I ran my engine an hour a day to top off the batteries.
While plugged in at the dock, I had an automatic battery charger to keep the batteries charged.
I found that the solar panels were not effective while sailing. In theory they can produce power, but just a shadow from the rigging would lower the voltage so much, it wouldn't charge the batteries. Bird crap on the panels would also lower the voltage. Plus they take up a lot of space. Not to mention that sailboats lean and are never at the right angle to the sun. They were only somewhat effective at anchor. In theory, solar panels are great, but in reality (on a sailboat), they aren't all that practical.
Now I have one 20W Flex Solar panel for the dinghy with an AGM Motorcycle Battery in a portable power box with a VHF radio. I have one 40W solar panel I only take out at anchor. Wind Gen (dedicated to refrigerator battery), High Amp Alternator, Battery Isolator, and Automatic Charger (while dockside) are my main charging system. The battery isolator is diode based so the alternator hits all batteries. I wouldn't have an objection to a voltage sensitive relay for charging an auxiliary battery. VSR's are cheaper than diode based isolators and don't have the .6v voltage drop.
The regulator for the Wind Gen is my homemade 3 phase shunt regulator. You can see it in the Controls section. It only shunts the load if/when the refrigerator battery is fully charged. Otherwise, the battery gets whatever the wind gen puts out.