Here are a few things that work for hotter weather, lower water SMB:
1) In the hottest weather, the bass will usually not be far from broken water. Sometimes, they'll hold in water you;d think would wash the hide off a trout, let alone a bass...
2) Regardless of the temperature, you can catch fish all day by fishing shaded banks.
3) You don't need dry flies unless that's what you really want to do. Generally, even during a hatch, river bass don't care about this stuff. Use a popper. But use a smaller popper than you think you need. You'll catch more smallies on a size 8 than a size 4 popper. Fish your popper everywhere you think a bass might be, including in heavier water. They'll come up for it.
4) In my view, the most versatile and effective smallmouth bass fly there is is a simple black rabbit fur leech, 2.5 to 3.5 inches in length. Sizes 4 through 8. Dark brown is also good. I think one of these leeches is worth a mixed bushel of Clouser crayfish and deep minnows. You can strip them (less effective) or dead drift them slightly off the bottom (most deadly, IMO). Another really good bass fly is Tim Holschlag's Holschlag Hackle Fly. Here it is:
http://www.warmwaterflytyer.com/patterns6.asp?page=2
A couple other really effective patterns are Harry Murray's strymph and hellgrammite patterns. Again, the strymph is best (IMO) in black or drk brown.
I think all these other subsurface patterns work best when dead drifted or gently "walked" along likely cover. But some guys swear by a deliberate or organized retrieve of some sort.
That's all I know...
