That's why they make those various adapters. It's perfectly fine to use them. However, I would not recommend adding any additional standard extension cords when using 15/20 amp circuit. If you do need to run longer to reach a plug keep the extension cord as large as possible (30 amp extension cord if possible) or us a heavy duty cord that is as short as possible.
You just have to be aware of what is and what is not running in the RV. There are a number of parasitic loads so a bit of experimenting might be necessary. I have plugged my Prevost bus conversion into a 15 amp circuit to keep the residential fridge running. I just have to turn most everything else off.