The subject regarding a "Level" tow bar directly relates to "Bucking" over road height variations. I tried to cover my experience with "Bucking"
HERE.
Regarding the effects of a tow vehicle on "Handling", that is well addressed by installing a rear trac bar. Towing anything from a tow vehicle to a trailer, will grab the rear of the motor home and thrash it side-to-side. A rear trac bar prevents the motor home from responding. It is the symptom often referred to "The Tail Wagging The Dog".
A rear trac bar should improve over-all handling under such conditions. Different upgrades help under their respective conditions. One upgrade does not address every condition, but some upgrades address more common conditions.