Common sense tells me that the trailer should be leveled and jacked before the slide is put out!
That being said, I do put the slide out before we leave on a trip without the trailer being leveled and jacked just so I can vacuum and load up without having to squeeze through the trailer while getting ready for a trip!
We park the trailer next to our garage when not in use . . . and there is not enough room to open up the slide when parked in it's storage space.
However, one of the reasons that we chose our Heartland Trail Runner was due to the fact that the trailer can be used when the slide out is in.
It is a tight squeeze to get from the living room to the bathroom . . . but no big deal!
Cathy and I are both tall and skinny (within reason
), so we can get through the gap with no problems . . .
Almost every other trailer we looked at was almost non-usable when the slide outs were in . . .
No pole vaulting required!
In other words, we can walk from end to end in our trailer when the slide out is in.