I have never seen so much poor advice on here.
No, there will not be fitment issues. A '96 F250 has the same standard size and width box as all the earlier trucks did. There is no camper that won't fit.
What do you think that camper rode on when it was new? There was no such thing as an F350 dually pickup in 1978. Yeah there was an F350 pickup but it was very rare and wasn't a dually. Everyone used 3/4 tons.
Come on guys, this is just a 9-footer on an F250. There's literally zero problem here. That F250 is perfect for the job, those two units were made for each other like toast and butter.