Should I use slideout supports?

No, do not use. In fact, they will likely do the opposite of what you want, which is to prevent issues with your slides. Your RV will flex and settle when you park it, and the support will restrict your slideout from moving with the RV, creating a stress point on your slide and potentially damaging it.

Don’t worry about supports.

@ia_camper is spot on.  Plus they may void the manufacturer warranty of your RV. Instead of supports, you can extend the life of your slideouts with:

• Regular Maintenance: Ensure that your slide-out mechanism is well-maintained. Lubricate the moving parts, check the seals, and keep the slide-out area clean to prevent issues.
• Proper Leveling: Always level your RV properly before extending the slide-outs. This ensures that the weight is distributed evenly and reduces stress on the slide mechanisms.
• Slide-Out Awnings: Consider installing slide-out awnings to protect the top of your slide-outs from debris and water, which can add unnecessary weight and cause issues.
• Avoid Overloading: Be mindful of how much weight you place inside the slide-out area. Overloading can strain the mechanisms and lead to problems over time.