It's probably able to be done if you could get the overall diameter of the wheels/tires to be close to matching for the front and the rear of the vehicle. Lots of performance cars these days will use a smaller front wheel and a larger rear wheel and tire combination. Corvette and Elise/Exige are 2 cars that come to mind first that run this staggered setup. On your Teg, you could run the 17's in the back with the 205/40/17 tires and the 16's in the front with a 205/45/16. The rear overall diameter will be 23.45" and the front will be 23.26". The sidewall height will be 3.22" for the rear and 3.63" for the front. Revs per mile for the rear tires will be 886 and 894 for the front due to the smaller diameter of the front wheel/tire combo. Your front wheels being lighter and having a slightly smaller overall diameter with also help a little with acceleration, etc. This is probably your best option with your current "hodge podge" set of wheels & tires. The front wheels are gonna have a little more sidewall than the rear but only 0.4 inches, nothing extreme or crappy looking compared to the rear. The width and contact patch for the F/R tires will be the same as before with the matching 205mm width tires you'd use. I work for Bridgestone/Firestone and on customer cars, we wouldn't recommend this fitment unless it was OEM spec. On my car, if I had no other choice, I would do what I had to do to make it work though! Good luck! Hit me up if you have any other questions.

P.S. I've run 205/40/17, 205/40/16 and similar low sidewall tires before and they are about the worst size tires to run for wheel protection. We both know that's the risk we're taking to have the "rubber band" look that so many people are after. I'm currently running a 205/50/15 wheel and tire setup and it has pretty good protection while not looking like crap with too much sidewall.