We also used an insect growth hormone inhibitor many years ago. It was called Precor - not sure if it is still available, or goes by another name these days. It only affects insects, and when sprayed on floors (especially carpets), it lasts for several months, and does not allow larvae to mature to adulthood, thus breaking their life cycle. You could use that along with the other products mentioned, and avoid the flea bomb. The Advantage / Frontline on the cat will make short work of the adult fleas already present. Our cats have not gone outside for years, so we have not had any fleas to contend with. But it worked great when we needed it.
Of course, fleas are just one of the many reasons to consider keeping your cat inside, or inside with access to a screened porch only. We had many cats back in the '70s and '80s. I got so tired of seeing them killed by cars, dogs, attacked by other cats, and catching feline leukemia and feline AIDS, that I finally gave up on the idea of outside cats entirely. Since then, the only cats I ever lost have been 15+ years old, and had to be put to sleep because of age related problems.
Anyway, if you avoid the bug bombs, and use the masking tape strips on the walls, barely brushing the floor, sticky side out, and check around every night with a flashlight after the house is dark and quiet for a while, there is a good chance you will find him. Once the cat is back inside, watch him carefully. He may well notice the snake's presence by smell or sound before you do, and can alert you if you pay attention.