slide supports haven't been necessary for at least the last 10 years of slides.
they are leftovers from the early days of slideouts or as they were called tipouts. the tech then was new and there were a lot of issues with them.
now, if you use them, you could void the slide's warranty. in fact, there is often a warning sticker NOT to use them.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC