Since at the moment you seem to be a high 4.5 - transitioning into 5.0, why don't you enter some 5.0 tournaments where you will be competitive and not as many open/pre-qualifying. Yes, it will give you some knowledge of the competition getting whacked 6-0, 6-1 or something like that once in a while by a true open or futures player, but it will probably help you develop more playing 5.0 people who are just a little better than you where you can have a competitive match. Yes, you may get a 4.0 you can beat up on in an open tournament, but that isn't helping your game. Once you start doing well in 5.0s, transition to more opens and less 5.0 tournaments.
Going from 4.5 to beating 6.0s is a big leap to take all at once. If you really want to do this, it's going to take a lot of hard work and dedication - do you have a life other than tennis? (wifes and such frown on this)