Bedding Deck Drains - Sealant Choices

I read and post regularly on and  message boards.  Forums and message boards have been incredible sources for information and opinions on any subject you can think of.  On most forums I post under the user handle "Beersmith" (I homebrew beer, "smith" like blacksmith").  Many of the topics I blog about I've already discussed on these forums before I post here, such as: New Found Metals: TRI-Matrix Ports Help with Refrigeration Decisions . . Large Cabin Windows - What Would You Do with them ? Cruisers: Pressurized Fresh Water ?

Here is a new discussion I started today concerning bedding hardware on my freshly painted decks.  I need some assistance in figuring this out, so either comment here or post on the forum discussion if you have any input:

Bedding deck drains - sealant choices?

After finally finishing the deck paint job (except the non-skid), it is time to install some deck hardware. Right now my objective is to get the deck and cockpit drains installed so rain has somewhere to go. The deck drains are all bronze, and the cockpit drains are UV stabilized plastic of some sort.

I had always intended on using butyl tape for items that will be bolted down, per Mainsail's instructions. However, these drains and a few other fittings are to be installed with small screws. It seems that butyl won't really work with screwed on fittings, only bolts.

What sort of sealant should I use for these fittings? I am adverse to anything "permanent" such as 5200. After taking my entire boat apart for this rebuild, I curse anyone who used such things on this boat. I read that polysulfide sealants cannot be used with plastic, so that is out for the cockpit drains.

Right now I am thinking either Boatlife Lifeseal or Sikaflex 291. Am I on the right track? Which would you recommend of these, or what alternative should I consider?

Also, I understand the techniques of bedding, but one aspect has me confused. I plan on using masking tape around and on the fitting itself to save the mess, applying the goop, screwing down lightly, let the goop cure some, then tighten down.

However, if I apply the goop under the screw heads, what technique do I use to make sure the excess doesn't get inside the screw head/slots when I wipe off excess?