So. Ask a question don't just add a question mark to a statement.
You have a trailer that is a little overkill- no big deal unless parking space is limited in the off season.

Even though you asked this in boating, I assume you mean a porch-patio deck and not a boat deck.

If your deck is already pressure treated, you are good against rot and bugs for ten to twenty years. If you want additional protection, buy Borate powder and mix it with water and slosh it around. Available at Jamestown Distributors.

If you just want a sealer to look good, much as I hate HD products, their Bear sealer part number 60 something.......is excellent. I just stripped, cleaned and stained thirty year old in the tropic PT wood deck and it looks fabulous.