I replaced my factory batteries with Victron Super Cycle batteries. They are rated for 300 cycles of 100% discharge, this allowed me to go with a smaller ah battery, shed some weight, gain some room in the battery compartment, and keep all my charging equipment. I sized my bank to routinely discharge to ~60%. I just couldn't justify the cost of lithium when lead acid would do the job for me at a fraction of the cost. I only get to camp about 30 days per year, so even if I fully cycled them I should still get 10 years of service.
If cost is no issue for you, then lithium may be the way to go. You may need all new charging equipment as well. Personally I would not be comfortable with lithium "drop in replacement" batteries in a camper, these usually rely on an internal battery disconnect to prevent over charging. It would be better to have a charging system designed for lithium that wouldn't try to over charge.