First, don't mix battery chemistries...it's really bad for the batteries, and gel batteries are about the worst IMHO.
Are you saying that you use only 5-10 amp-hours all night? I find this very hard to believe given you have a refrigerator, and most of them draw more than that. Add the cabin lights and nav lights, and it goes up even more.
You really need to come up with a fairly accurate electrical budget, preferably a worst case scenario one that overestimates your electrical usage, rather than underestimates it. Then you have to figure out how many days you want to go before having to recharge the batteries. Multiply the number of days by the daily usage and then double it to get a rough idea of the size of the battery bank you'll need as a minimum. Then figure out passive recharging systems you have or are going to add and how much usage they'll offset under the least optimal conditions and subtract that from the battery bank size.
Ideally, you don't want to run your battery bank down below 50% very often. The batteries last far longer if you don't run them down below 50%.
BTW, do you have a battery combiner?? If not, getting one might not be a bad idea. Also, get a good external voltage regulator for the alternator. Not only will it help the batteries charge more efficiently, it will help prevent the alternator from frying them.
Thanks for asking camaraderie,
I have a 200 A house bank, AGM, and a 75 A start battery, GEL. I had heard that it wasnt good to have two types but thats the way the boat was set up when I got it. I figured if I was slowly killing the Gel battery, so be it. I have a Trucharge 40 for when Im at marina (which is most of the time). Im trying to set up for 2-3 week trips but more than a weekend but not cruising. I have frig, lights, chartplotter, radar, autopilot. So while at anchor Im using maybe 5-10 amphr in evening with lights and less during the day. When sailing with radar and autopilot, use goes WAY up. Could be 30 if radar is radaring and autopilot is struggling, even more at night.
I have a 50 amp alternator and no external regulator.
Does this info help with suggestions from you.