Yep... Dovo pins would do the job. As for sealing the rubber..... My personal choice would be to loose the rubber and not bother, but if you must..... RTV silicone would be my choice. Do not confuse RTV with regular silicone caulk/sealent. RTV releases a solvent, regular silicone sealant releases acetic acid, aka vinegar.... and will corrode the area even more.

The problem with sealing an enclosed area covered by rubber is that you never really know for sure that there isn't a void under the rubber where moisture could accumulate.... If moisture gets in.... corrosion follows promptly. If the rubber collar is clear, you can see any voids.... if it's black.... well, you'll never really know, until it's too late. If you are really really really careful when you fill the rubber cover with RTV and you are dead nuts sure it does not have any voids, you'll be just fine. It comes down to the "dead nuts certain" bit..... and only YOU can know if you are confident or not.

Regards

Christian