Thanks for the kind hashtag, and sorry you have to deal with the bearings.
PSA: do NOT put your trailer into the water when launching. Unless you like repairing wheel bearings for fun.
No clue on which bearing sizes to use, but for a used dolly, you can reach out to various harbormasters at Bay Area dry storage areas to see what they might have laying around, which you can hopefully buy for a nominal fee. ACSC, Richmond YC, PYSF, SFYC, StFYC, Sausalito YC, Encinal YC, all have junior programs, which tends to lead to abandoned dollies over time.
For instance, ACSC has a dolly wheel graveyard in the back; you could ask Mike Bishop if you can buy any of those.
You might get one piece at one place, and another somewhere else, but if they’re all Seitech or Dynamic, they should all fit together.