You are right about the 240v being, essentially, two 120v lines. �Unlike
120V, which has a Hot, Common and Ground, the 240 has (or can run on) 2
Hot and a Ground/Common. ...

To clarify for OP what could be misinterpreted given it appears little or
no familiarity exists...240V has _only_ two 120V 'hots' and an associated
ground, _no_ neutral.
Bill

Too much in your message(s) to really make meaningful/rational
comments.

So please get some more learning.

Also be aware that the RV power you mention is probably 30 or 50 amp
power. Sure it is 240 volt? And too small for the shop enviorment you
mention.

Where and how 240 volts is sourced to the consumer, has been mentioned
here, but the details that transform the high voltage on the power
pole or in the power vault that is near you property line is more
complex than what has been mentioned here.

If you add a power (sub)panel that is sourced from your service panel
remember that are limitations in the code. The neutral and the ground
need to be separate and not connected circuits.

Bob AZ