You can stay hooked up if you are able to get the camper level, or close to level without unhitching. If you are really out of kilter, then you do not want to operate your slides. As stated above, that will put undue stress on the slide out system.
You did not indicate what model of camper you have. The "Montana" line has hydraulics; the High Country Line mostly has cable; there are some that still use the Rack and Pinion system. I think the Rack and Pinion system is most at risk if not level as the rails and augers under the slide could bend or bind. Cables can get over stressed if all the weight is on one cable and not the other. Also, cable slides have room to move as they are simply sitting in a hole and ride on rollers and the floor above those rollers can shift forward or backwards, causing extra tension on one end of cable or the other (eventually breaking).
So, in order to play it safe, unhitch and level. If your campsite is long enough to remain hitched, simply unhitch and pull the tow vehicle far enough forward just to clear. When hitching back up, you are still aligned with the king pin, simply back up a couple feet and hitch up again. This take virtually no time or effort, provided the tow vehicle is still directly in front of the hitch.
