RTVLady, I don't have an RTV but I do use SLIME.
I've got a couple hundred native Hawthorn trees on my land and they have thorns that average about 1.5" long and can easy poke through a tennis shoe or a tire. I lived with constant flats for years and then I learned about SLIME. I SLIME my garden tractors, wheel barrows, trailers, etc and have never had a flat in any tire after the application of SLIME. It just plain old works. There are other brands on the market, Gemplers sells a brand (or they did, I have not checked lately) that is rated for high speed road use in addition to a version that is similar to SLIME. You should not confuse these products with items like Fix A Flat or Air & Repair, those are different types of items and would not be used in the same way that SLIME and similar products are used.