If your authorised representative in the EU put your products under his/her own name, then she/he takes over your responsibilities. In this case he/she must have sufficient information on the design and production of the product, as he/she will be assuming the legal responsibility when affixing the CE marking.
Many of the larger inverters come with a built in charger. Typically a 2000 Watt or larger inverter will have a 50 to 100 Amp 3 stage charger. These are much better than the typical RV converter/charger. If you are planning on a more powerful charger anyway, the combo units make sense.
If you have trouble finding suitable wire for your RV inverter install, automotive battery cable or jumper cables are readily available in 4, 6, and 8 AWG (American Wire Gauge). Welding cable comes in larger sizes, but is expensive as many times you have to buy a whole spool.