Installing an armstrong bracket

[JohnB]

All,
I just got the bracket back from the powerder coating place and it looks great. I am going to be installing it this week, and had a few questions.
1. I am going to use the rubber backed washers against the bracket to keep from chewing into the powder coating for both the mounting and engine bolts. I know that the rubber has carbon in it, which is bad for aluminum, but the tradeoff would be cracking/chewing into the powder coating. Anyone have any better ideas.
2. I am going to use 5200 to seal the bracket, especially the tub. Any better ideas to make sure the floatation tub stays dry? This is an Armstrong with the tub facing the transom being open.
If anyone else has some tribal knowledge they want to pass along, please do.