X2
If you remove it and use the roof vent fan the ceiling around that fan will be covered with dirt from the steam and grease from cooking etc. because it will suck all of it right up to your ceiling.
You can say you don't cook messy things. Well just boiling water or cooking vegetables, frying an egg, etc will be sucked up all over your ceiling. What doesn't get sucked up by the fan will end up all over your furniture. Over time you WILL see the results inside you RV of removing it.
That range hood may look worthless but there is a screen/filter in the hood to 'prevent' all that stuff from covering your walls and ceilings.
I wouldn't do it. just saying.