The route to Otisco might be a little snug with a 40' 5w, and it's not any closer than Turning Stone would be from SU. Never stayed at that campground on Oticso but I know the area - very nice, quaint little area of the Finger Lakes and close to the wineries if that's your thing. Turning Stone is an easy trip comparatively - from SU proper it's 30-40 minutes. You're on the Thruway about 20 minutes. The Stone has a nice steakhouse, phenomenal golf course, and (of course) the casino. The rv park is top notch. For ease of getting there and back I'd go Turning Stone. If you want more out of the way, Oticso Lake is nice.
Outside of that, it's slim pickens for full hookup campgrounds that close to Syracuse. There's a Jellystone in Mexico with some full hookups but it's all of 45 minutes from SU and you'll be tight with a 40'. Everything else is an hour +.