Lithium battery

The keys with a lithium conversion are:

place the battery in a heated location, never charge a Lithium battery below freezing temps.

the battery must have a battery management system (BMS) that equalizes cell charge voltage and protects the battery from overcharging. The BMS should come with the battery and is typically internal.

Convert and/or reconfigure all charging sources for Lithium battery use. Those include the on board Ac/DC charger, alternator charging from the tow vehicle, and solar charging if you have that.

The on board lead acid battery charger can be swapped out, and most modern solar charge controllers have a Li setting.

Generally the alternator charging is the most complex to convert. You do not need to run a separate charge circuit, the +12V pin on your 7 way connector will work. You need to run that into a DC/DC converter located in the trailer, before that wire connects to anything else in the trailer. The DC/DC converter should be sized based on the ampacity of your 12V trailer supply. That will typically have a 3O amp breaker so a 20 amp converter would be a good choice.

You will either need to disconnect your 7 way whenever you stop for more than an hour or so or set up that circuit with a relay so it's switched off when the ignition is off (some already are), otherwise the converter will happily continue to charge the Li battery if it is low,discharging your tow vehicle starting battery in the process.

As you can see, much of the cost and most of the work is involved with the charging sources and wiring, not with the Li battery itself, which is getting pretty inexpensive now.

Not in a 195, but in our 179, you can read about my conversion in my mods (see link in signature).