How many batteries do you have, and how many do you need to replace?
If you have a typical trailer with two batteries on the tongue, replacing the two with one LiFePo may be sufficient. That is what I did in my first conversion, and could get easily three days of summertime camping before I needed to charge up. That is with dry camping in a TT, no AC use and not much need for heat.
Check that your converter has a lithium charging profile.
Many TT have the converter some distance from the batteries, and since the charge rate is low (0.2C or lower) the wires are fairly small. You can still charge your Li battery, but it may be slower than it would be if you had short, fat wires.
2018 F350 Limited
2021 Outdoors RV 24KRS
2021 Arctic Fox 27-5L