Depending on the weather, the Bechler area may not be a great option even in late July. The area is quite marshy, and if you're hiking in, you'll want to wait for most of the marshes to dry up. Late July may or may not be OK. Even if the marshes are dried up, be prepared for some killer mosquitoes, beautiful waterfalls and good fishing in a great part of the Park (a few years ago this part of the park could have been said to be relatively unpopulated with folks. its not that way anymore).