Its always smart to check the voltage upon arrival before unhooking or plugging in. You can do that with a cheap multi meter. I use one off Amazon that is AC/DC with a Hertz mode. While your there you could just have a voltage meter plugged into a wall outlet, that way you have an idea if your getting enough volts.
Progressive Industries EMS hard wired in is best if you want good protection from high or low voltage, bad grounds and surges.
My minimum is something like this for checking out AC outlets and DC batteries:
https://www.amazon.com/gp/product/B07Z398YWF/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1While I'm in the RV I use one of these two to monitor voltage:
https://www.amazon.com/gp/product/B015H0A3FO/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1https://www.amazon.com/gp/product/B081ZL5PCV/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1EMS for 30 amp, they make a 50 amp also:
https://www.progressiveindustries.net/ems-lchw30