Why don't you put a frame on the bottom of the slate?
I framed my slate with 1 X 6 poplar from Lowes. Cut it to fit and glue it on with 3M contact adhesive. Drill the holes for the slate bolts and you are done.
You can't notice the 3/4 in height increase. The table plays much quieter.
Now I staple on the cloth and can stretch it much tighter.
Kim
That seems like a whole lot of extra work to get the job done. Depending on the level of the floor, that 3/4" might take your playing surface height out of spec. Chances are you'll have to replace your rail bolts as they won't be long enough to go through the extra 3/4". That's a lot of cutting, gluing and drilling that, although isn't hard, you need the right tools to do a good job. Besides, if you have the 3M-10 to glue the backing on, why not just use it to glue the cloth on?!? You can get the cloth stretched on just as tight and more evenly with the glue as you can with staples. I didn't believe it either until I saw it and tried it. The only advantage to adding a backing to a table designed for unbacked slate is that it will play a bit quieter.
The guy that didn't recommend Simonis on an unbacked table said that because he doesn't know how to properly install Simonis and isn't able to get it to stick. Simonis CAN be installed using 3M Super-77 spray glue if you know what you're doing, but 3M-10 works perfectly for installing it. Get a mechanic that knows how to work with Simonis, and you'll be just fine on that table.
