I don't know much about this stuff either.  I was thinking of getting
an inverter so that I could power up a space heater for those cold
off-season mornings & evenings.  The heater that I have is 1500W.  Does
that mean I'd need to get a 1500W inverter?  I wouldn't be using it
without the van running, but it would be more efficient than the van's
heater which can take so long to heat the space up.

Any advice would be appreciated.

Thanks,
-Robyn.