John,
I agree, more truck is definitely better. The Casita, loaded, comes in around 3200 lbs - in theory, our 2002 minivan could tow it; I could take Marias Pass through the Rockies, a pretty gentile climb and drop, but I'm pretty sure we'd have a dead Caravan long before we hit the Eastern time zone.
I'm pretty confident that a relatively newer 1/2 ton, with add-on electronic brake control for the trailer, will handle rig, but I'll take a look at the 3/4 tonners, too.
Regards,
Scott