Anyone know where this dust is coming in from and how to seal it? I used foil tape and silicone under the plastic bedside caps before the camper was installed, so I don’t think it’s the holes in the top of the bedsides. Are there larger holes under the bed rail on the third gen Tacoma?
It's very very hard to 100% seal everything. I use butyl and Sikaflex under the bedside caps and I still get some dust here and there. I suspect one of the reasons is the bed deflects quite a bit, especially with the weight of the camper in. When deflection happens, gaps will open up and will let dust in.
My solution was to put the full Bedrug kit on the bed before adding any accessories. This way any dust that comes in is trapped under the rug and doesn't come to the surface. Also, it acts as a very nice insulation.