Charging voltages change with temperature. The PD bulks at 14.4 and floats at 13.6. These are ranges that should be acceptable for your AGM batteries. These are also the recommended charging rates for some LiFePo4 batteries such as the Battle Born brand, so it should work ok for that as well when you upgrade.
Victron does make a very nice line of MPPT charge controllers (without inverter) that are reasonably small, are 100% adjustable for voltages as well as temperature fluctuations. They have many depending on your needs. This is one that will charge up to 50A
Victron 100/50If you leave the stock PD and just add an inverter you will need to think about how you wire to deliver the power to the camper. Depending on the camper adding receptacles may be easy or not. Some people just add a plug or two where they would need power such as kitchen, behind the TV etc.
We plan to run a large inverter to power the entire camper that we can switch on and off from inside. Mostly we use 12v. power or small local inside inverters for things like tv. The large inverter to be turned on to run high load devices only.
Here is Lifelines recommended charging voltages at variable temps. Unless you get a sophisticated programmable charger with temp sensor you sort of need to find a good compromise. The stock unit is a good compromise