BurbMan wrote:
Generally NOT recommended by any mfr due to the potential for damage...if the TT settles or moves and the slide room does not due to these supports, you risk mis-aligning the slide mechanism and causing operating issues with the slide.
Stabilize the trailer frame when you park and the slide out will be fine.
The manual for my Kodiak (Dutchmen) says you
should put a support under each slideout if you are staying more than a couple of days. There is little chance that the TT will move if properly chocked.