Thumping won't work on melon blossoms because the male and female blossoms are totally different flowers. In tomatoes, the male and female parts are in
one flower, but not so with the melons. Sorry.
Do you have a lot of bees in your garden? Attracting some bees would be your best bet for lots of pollination. They like salvia and many flowering herbs. If you can plant some basil or flowers around the area it would help.