I think most owners are saying their Venture 23s are weighing 5,500 pounds and up. CD-22s seem to range 4,500 to 4,800 pounds all up.
I understand your frustration - that Grand Cherokee is a great vehicle. We had a campervan on a Dodge one ton chassis that had an 8,000 pound tow rating when we ordered our CD-25; we thought that would be a great pairing for traveling. After hearing from other owners, we realized that wasn't going to work - bought a 3/4 ton diesel pickup... which was a great match up with the 25.
There is a LOT of difference between the CD-25 and the V-23 or VD-22; not just in the weight but in the volume inside the boat. There are plenty of couples who are happily cruising with 22s. BUT, if you want more elbow room, more storage, more amenities (fridge, 30 amp electrical system), a full hot & cold pressure water system, and an enclosed head with a shower, the 25s have that, the others don't.