I haven't even picked up my Tavor yet (I will this afternoon, Cant wait!!) but I found myself looking at alternatives to mounting a tac light even before I placed the order for my Tavor.
Several times I have had my "Cart" on various websites filled with all the aftermarket add-ons needed to attach an under barrel tac light, but each time I have changed my mind.
After watching several videos of the Tavor in action with the IDF, I have decided to give the side rail attachment of a Tac light a chance before I go changing out hand guards.
I plan to use the designed pressure switch in the hand guard first as well, and if that set up dosen't work for me I'll start looking at the aftermarket forearms again.
I also went around and around about optics for my Tavor as well, and ended up with ordering the Meprolight Tru-Dot RDS...
OP: Just a suggestion, but if you like the placement of your Tac light, maybe you could try adding a set of BUIS to your rail. Place the front sight behind the light, and the rear behind your red dot???