The way for you to have any amount of sucess going over that gloss floor paint will be to sand the gloss off, which will be a big job even with an electric sander. There is a solid deck stain made by the Flood Company that is a latex/oil mix and you get the best of both with this product and it does dry flat. But bear in mind now you have an oil based enmael on your deck and the back side is not sealed and moisture will be able to enter here and eventually that oil enamel will pop off.This is going to happen anyway so if you can't stand the gloss finish you now have go ahead with the solid stain from Flood.