Have you looked in the Towing Rigs forum? There has been a lot of discussion about the Odyssey as a tow vehicle.
As far as older TM's, AstroBruce just posted a very useful link to older TMs.
http://www.trailmanorowners.com/foru...ead.php?t=8187
Even with that, though, it is difficult to make a direct comparison. Items such as a spare tire, which used to be considered an option (and thus not included in the dry weight), are now considered standard items, which makes the new models look heavier. Just be aware that heavy items like the air conditioner, awning, swing tongue, and maybe battery are still not included in the dry weight.
And yes, it is wise to travel with no water if you know you will have hookups when you arrive.
Bill