If sailors just move around from one dock
to another in Marinas
what you say is almost true about "being in the same boat."
However, if your RV were built substantial enough to endure a rollover and keep on going or stand up to gale force winds while still moving or keep on going for a month without stopping or seeing another RV then it would be nearly the same as an oceangoing sailboat.
True, the 12 volt electrical system
can be nearly the same except sailboats need more battery
power because they are off the grid more.
Anyway, I think there are similarities in systems but each is built for a different purpose and can't really be compared fairly.