As a boat owner who has been screwed, listen up.
You have many things to consider, one of which is water penetration. It doesn't matter what you bed with, water will find a way between the environment and the insides. What are you screwing into? Will water ruin it somehow, ever, be absorbed? Is the item you are screwing into one solid piece or a composite of layers. Water will spread between each layer the screw penetrates. In every case on my boat where there was a screw there was substrate, lamination, and soaking damage even with goo squeezing out. Any absorbent material will never be satisfied to be dry in a wet environment and will never release the moisture by free will. Fragile lamination is 100% absorbent. Capillary action can travel 100's of feet up against gravity.
Ask yourself if you are capable of repairing the water penetration damages later, why did the bimini break off in the first place?
In all cases I had to use a screws again, the cure was to ensure that the laminating layers within were sealed and none of the laminating layers were absorbent or had layers for capillary action. I also replace anything that water can damage with a water safe replacement, in my case G10 backer board replaced the wood for something the screws could bite. The G10 was epoxied into the structure. I also let some screws go 100% though from exterior to interior. It's sealed internally, so there wasn't a need to worry about water penetration.
The screw essentially needs to be bedded like a bolt where the the drill hole is enlarged and sealed. If all the laminating layers are sealed then it doesn't matter if attached piece is covered with 5200, butyl or silicone, water will flow in and have nothing to do there. It won't leave, but it won't accumulate either.
In one case of mine the manufacture had a screw penetrate the gelcoat, FRP, and foam in a centerboard (100% below waterline). Nothing rotted, but water seeped through the threads and got trapped in the FRP/foam layer. My solution was to create a solid piece of epoxy from the gelcoat all the way into the foam so that the screw never touched the layers.
In other cases the screws penetrated the outer covering of plastic, into wood, into foam, through FRP and into wood again. The wood rotted (100% above waterline) causing cracks in the outer layers.
Seal the screw 100% inside and you won't need goo.
