I have owned an arctic fox truck camper for 6yrs before my new Nash trailer. We used the slide (sat at dinette) many many times with it in. Never thinking anything of it and never having a problem. With our new Nash trailer we have done the same and used the slide with it in a few times. I emailed northwood after reading this conversation and asked them if it was OK to do this. They told me it was perfectly fine to use there slides in either the in or out position. So I guess it's going to depend on the mfg and what they recommend. If the told me not to, I would cease using the slide while in.
