Here are some thoughts on your system and upgrades:
I am a believer in set and forget systems. Wire the alternator, charger, etc to the house bank and isolate the starting battery. Use a combiner to tie the two. Yandina, direct or through Defender, makes a tried and true combiner.
Your simple regulated Mitsubishi alternator is almost worthless for charging a house bank. A few years ago I spoke with Balmar
about the largest single
belt alternator they would recommend. The guy I talked to said he used a 120 amp on his 27 hp Yanmar
and it worked fine. You can always derate the alternator's ooutput with adjutments to their regulator
. If you install a HO alternator, use a premium belt and keep it tight. Too much time and money
to install a two belt alternator for the benefits, IMHO.
1000 can only put out 800 watts continuously and that is about 6.7 amps DC. Check the specs on chargers. IOTA
even though not "marine rated" makes nice, efficient chargers. Their 30 amp charger will be real close at 7 amps max AC. This will probably work as maximum current for most chargers only lasts for 15 minutes or so until a charge builds up in the batteries. Depends on the size of your house bank. Get the one with the integral controller.