I'm looking for a guide to do some Smallmouth fishing with on Lake St Clair in July. Any input would be appreciated.

I have been going to lake St Clair for 20 years and without a doubt, Marcel Veenstra  www.marcelsguideservice.com will put you on fish.  Absolute best on the lake.  Book now because he is normally very, very busy.  Both he and his other guides are top notch.  

While I don't know any guides, you can rent fishing boats from Carina's Marina in Fair Haven, right by the mouth of the St. Clair River if that's an option for you.  That area we locals call the flats, and the smallie action is hot year round.  That particular area is also great for musky fishing if you feel so inclined.  Also lots of big perch, gills, and rock bass in that area.  During July, it's best to get out early as the tuna boats start congregating in Muscamoot Bay in the afternoon.  https://www.lakestclairguide.com/service/carinas-marina/