Pat, I am using a Renogy battery on my "car/suv" system. It is a generation before the current ones, and I do like the Renogy. Mine has a "storage" function, which limits the self discharge (which is very low to begin with).
I assume that you are choosing the more expensive self heating battery because of potential temperatures below freezing or below Zero F. Are you really planning to use this battery in sub freezing weather? Where will it be located in the boat? Will that place be below zero or below freezing?
I always refer people to:
to Will Prowse's U Tube site. This Renogy is on the battery I own.. Will gives this battery high marks, and one of the reasons I used it. Prowse's only negative is that this battery cannot be used in series. That is not an issue for you, since you will only be dealing with 12 volt (actually 13.4 volt) systems. The 100 amp hr battery will do fine for the one freezer/refrigerator. (And I was running an ARB freezer in my system)
You will need a battery to battery charger. With the 54 amp output (>30 amps available, I would suggest the Renogy 20 amp (they also have a 40 amp) Battery to battery charger. It has a temperature sensor--which I consider an excellent feature. It can also be current limited (I have not read the manual, but I suspect that would be a feature which you would use to charge the Li battery when you are at home or marina and still use the 10 amp Guest charger to the start battery. I have a separate 10 amp charger for my "portable SUV" unit. There is also an "ignition Switch" so its use can be limited to either only when you are running the engine, or you can use that to turn the system off, or on, when the boat is at the dock.
You should be able to do one of several things with the solar: One would be to dedicate it only to the Li battery. Another is to use it on the house, and then combine house and start--and then use it to charge all 3 batteries (the Li thru the Battery to battery charger. Or you can use a double pole double double throw switch (this is a switch which takes both neg and pos leads and transfers from one system (house battery) to another system (LI battery). This would require that you
change the controller settings between FLA and Ii settings.
As we develop what your goals are, and how much of the time you run the engine each day, how much the solar really contributes, etc. I wonder if you really need the "self heating" function? The Blue tooth monitoring is an excellent feature and worth a few extra dollars ($40, which will work on any Renogy battery (I might get one to play around with on my older battery, although I have an external monitor). Vs the specific monitor for Renogy: ($55 which does have some nice features, including a remote to put the battery in storage {shelf} mode).
It sounds as if your FLA are at the "end of life" (EOL), and you will be replacing them--or at least the engine start battery.
Don't forget to fuse everything. I fuse the wire from the B to B charger to the battery at both ends of the wire. Of course fuse the LI battery output to either the freezer circuit--or if used as a house then to that use. Also fuse to the MPPT controller.
As to those who say it is cheaper--yes it is cheaper. There is no question about that. But consider the weight, and you can get a lot more "power" out of these batteries. For example, I started with one 100 amp hour Battle Born battery, and soon migrated to two 100 amp hour batteries. I was running two refrigerator freezers, an induction burner, and a microwave--all my cooking was done off these two batteries, thru a Victron Multiplus 2000 watt PSW inverter, 80 amp 110 volt charger (you can charge the Li Fe batteries much faster, up to C1, which would mean 100 amps) and the Multiplus, has a built in transfer switch between mains or generator power--and inverter power. Also it will boost voltage to 1120 volts and provide a brief overload on the mains circuit up to 50 amps. Great feature if you are at the end of the dock and the 120 volt power is really 90 volts (not too uncommon at older docks)
To do all of this with FLA battery would take 2 8 D batteries. (200 amp hours each) at a cost of $400 each and weight of 130 lbs each: total 260# vs 52#.
Many RV's and higher end boats are now coming with LiFePO4 batteries as an option and a few as standard. Many of the bass boats, and sport fishing boats are using nothing but li batteries with their trolling motors. So the LiFePO4 battery has become mainline. (My son paid over $6.00 a gallon of regular gas in Calif. when we talked 2 days ago--a week's worth of gas all of a sudden may cost $600 dollars or if you have a C Dory 25 a fill up will be over $700). The Tom Cat 255 fill up will be over $1000 many places. Perhaps this puts items in prospective? Not sure. But I am glad my Caracal Cat gets 5 miles to the gallon! (And our prices are not that high in Pensacola.),
As Pat developes his system, there will be a lot of question, asked and hopefully answered.
Colby