Camping together? What relationship? You can get zip-together sleeping bags Can one get a hot and cool bag to zip together? Look for bags that have a square foot area and zipper that goes all the way around so the bag opens up flat.

One important thing is insulation from the ground, so a good ground pad may well be worth more than a thicker sleeping bag.

As mentioned above, wear clothes in the sleeping bag. Something like a fleece sweater might serve multi-purposes including an evening & morning camp shirt, as well as for riding on those cool or wet days (with a slicker as needed).