It's okay if you count the carbs - sf doesn't mean carb free but they're usually pretty low carb. Squash isn't ideal because it often contains citric acid which can be a staller - but I use it sometimes with no problems, just make sure you factor the carbs into your 20g.
Mostly I drink tea with alpro and sweetener in a large mug. Very easy to drink, and I sometimes have a coke zero which doesn't contain citric acid. You need to count the carbs in diet fizzes too - some are quite carby.