Well, you’ve sold a “nice” camper with a slide, in a market where a new one is certain to not be a financial bargain, so presumably you’re set on the no - slide thing already.
I guess I don’t see what the question is.
It’s literally more space inside vs one less potential mechanical item that may need repair at some random time in the future.
And presumably you can imagine what the smaller space is like. If not, I would have suggested camping with the slide in prior to selling the old camper.
If you are just wanting the moral support that it’s ok to spend more money to effectively downsize in 2 directions, you have my vote. It’s ok!
Congrats on your future new camper!