It will work just fine if done right, but it's also a huge hassle, and you'll be messing with your regulator and valves nearly constantly for the life of the kegs. I think most people would much rather either buy another regulator and do it right, or simply drink all their beers at the same carb level than go through all that hassle, but to each their own.
If you try this, you're going to want to make sure that the less carbed beers and the higher carbed beers are never connected to the gas at the same time after they've been carbed. You're also going to want to have a check valve on each gas line for when (not if) you mess up the order on switching things around or forget to vent the lines or turn the pressure down before swapping.
As for strategy, carb all the beers together to the lowest desired carb level. Remove the beers you want to stay at that level from the gas, increase the pressure to whatever corresponds to the carb level you want for the higher carbed beers, and let it/them fully carb. Once everything is carbed to the desired levels, if you want to serve one of the less carbed beers, you'll have to shut the gas off to the keg/s with higher carbonation, then shut the gas off at the tank, vent the pressure from the lines, turn the pressure on the regulator way down, connect the keg/s you want to pour from, turn the gas on at the tank, and then turn the pressure up to whatever corresponds to the carb level you chose for those kegs. Every time you want to serve from the keg/s at the higher carb level, you'd repeat the above process except that you wouldn't need to turn the pressure way down or vent the lines. As you can see, that's a lot of steps and hassle just to pour two beers that have different carb levels. If you had firends over for a tasting, you'd probably spend more time screwing with the kegerator than drinking beer.
For proper pours and a balanced system, you're also going to need longer lines for the beers with higher carb levels to prevent foaming. If you're going to have a lot of different pressures (carb levels) over time, I'd just make all of the lines overlength, and live with very slow pours for all of your less carbonated beers.
My advice is to try serving all of your beers at the same carb level for now, and see how you like it. If you find that it's lacking, and you really want another carb level for some of your beers, save up for a secondary regulator.