Look for something similar- It was about 5 years ago I bought mine at costco
Suggest you look for something which is DC native ( uses a wall wart transformer for home use) then operation doesn't require use of an inverter- most devices of this type run on 14 volts dc- which will work in your van - nominally 12 volts
digital native- to do away with convertor boxes on the antenna
audio? my original tv used a 1/8" stereo headphone type jack to feed the RV audio system-
find a tv which uses same if that's what your RV has ( remember I have a 2006- I don't know what your 2009 has)
a media player with usb is a great feature
as for mounting I adapted some metal brackets- newer TV's have a standard spacing for mounting on the set, screwed in the wood on the backside of the door
this 22" ( or 21.5) is the largest which could fit- notice it is not centered to the door and overhangs on the left
good luck with your search
this lg of a similar size shows it's DC native- the rest you'd have to search out
https://www.lg.com/us/tvs/lg-22LJ4540-led-tv#
Mike