I have the same problem where I sail. My boat weighs in at nearly 400 lbs. On a slight incline I can move it around on my own with the beach wheels. But on this beach it takes tow of us an enormous amount of effort ot get it up to the trailer.

I launch at a public beach so I can't install anything to make my life easier.

I was thinking that putting a winch on a post past the top of the grade would be a big help. All you would need to do is have one person keep the boat balanced onthe beach wheels and one person run the winch. If you wanted to sail solo you could use 2 sets of wheels.

This seems to me to be the most robust and the least expensive option for solo launching.