Never use silicone on your rig. For the roof, yes the self levelling Dicor is the stuff to use. For applications on vertical surfaces such as exterior walls, Quad is a good choice, or if you can't find that Geocel Pro Flex. DO NOT USE SILICONE.
2013 F-150 EcoBoost MaxTow, Roush tuned (415hp 506tq), lifted on 33s, R.A.S.
2013 Jay Flight 28BHS Elite (Equalizer 10K hitch)