The Dicor Self Leveling Sealant is great for roof seams/around vents etc.
But doesn't work very well on vertical/sidewall needs.
Dicor makes a non-sag sealant.
For vertical/sidewall sealant..... ProFlex Flexible RV Sealant by Geocel Corp. NOT FOR USE ON RUBBER such as EDPM roofs
The windows, compartment doors, furnace panel, water heater frame etc. used a butyl tape sealant when being installed and unless you are removing to repair no need for extra sealant around the edges.
Silicone should NOT be used.........silicone leaves behind an all but permanent coating to which no sealant, including fresh silicone, will adhere. If a silicone has been used it must be completely removed using a silicone remover.