Douglas fir is about the same weight on average as a one made of poplar. I don't have a poplar Tele, but I do have a hard-tail poplar Strat that weights 3.35 kg (7.4 lbs). You usually don't lose more than about a pound by chambering...so you might get it down to the another half kilo or so. But you would lose some strength, and I would worry a bit about splitting, particularly if it gets dropped.