The information I'm finding on the 9-1/2' Jayco Sportster indicates that it was manufactured in the 1980's and 1990's. So it is almost certainly a long bed camper.
A short bed camper will have storage compartments added to fill in the 18" gap between the rear of the camper and the rear of the truck.
As with the other "long bed camper on a short bed truck" I just replied to, your main concern is STRUCTURAL. The camper was likely designed to be transported with the first 8' of floor supported in a long bed truck. It may not hold up to having the extra 18" hanging off the back, but there's no way of knowing without trying.
If you don't have much invested, the worst that can happen is the camper starts to sag in the rear and you'll have to stop using it, or you can keep using it until it's so bad you have to junk it.
Some people have had great success with long bed campers in short bed trucks.