They do make a mount, I can't seem to find it on google right now. Basically a short mount L bracket you secure to the top of the swim platform and attached the outboard laying down. I never bought it because then you have a bracket in the way on the swim platform. If you can come up with a quick attach mechanism then it would be much better.
If you wanted to get creative you can get a davit quick attached and mount an L bracket.

The other thing you can do is put a bracket on the 248 stern. Not sure if the back of the seat is strong enough you may have to use the corner. But something like this https://www.anchoring.com//products/stainless-steel-auxiliary-outboard-motor-kicker-bracket?_vsrefdom=adwords&gclid=CjwKCAjw0ujYBRBDEiwAn7BKtwEmoSYiW82NhFqE_9GAgrN0mKFkrDQvIBb9KX4QLl34p9DUI-IWmhoC2y0QAvD_BwE

I usually put it on the floor in the aft seating area of the 258. Was in the way but only came with us on over night trips. The other idea I had was build a small box and secure it on the bow to the rails. We would bring a 9.5' roll up inflatable with use and that's where I put it. Tied it to the bow rails on port side so I can see better driving. We hit some large waves and it never went anywhere. A box will be slippery and will move, securing will be harder.