I would like to know if the hole can be realistically repaired, to
last at least through the end of the summer. I am aware of existence
of vinyl repair kits, but am not sure how well they work.

I used a vinyl repair kit once and it worked for a while. Your kit might be
better.

8 years my little derelict tied a canoe up so the waves ran it against the
dock, which wore a hole in it. I put duct tape on it which lasted a year.
Then I glued the tape down with Eastman 5200 (I think that is the number, it
is a black caulking glue) and it is a good as new after 7 years. I love
that E5200.

I keep meaning to do a fiberglass repair, but you know how that goes.