The only way to get mature melons here is to limit the number of fruits on each vine. One or two is about it. I don't know if that's just a short season response, or if it's due to the fact that we generally don't get any summer rainfall. One of the best tasting melons we ever had here grew in with the roses.
I can't do the plastic or covered beds. Some kind of varmint always gets beneath it and digs holes around my roots, and I don't see them until it's too late.
Top-dressing with mulch seems to work better with our plentiful wildlife. The couple down the road from us grow a market garden, however, and all of their beds are fabric covered, so I guess it just depends on the situation.