Question on portable waste containers

I use the Thetford portable tank as well. Wheels are heavy duty and the handle is designed to tow it. On a 4 night stay I usually dump the Gray water 1 to 2 times, but the black is good until leaving. I have dumped the black tank on extended trips though. These are on sale at camping world with free shipping at the moment. Never had a spill or issue towing. There is a little red indicator that pops up when it is full - I usually don't fill it to the top - but that's just me. I'm not sure I could ever break camp and tow the TT to the dump station and get it back and set up again before having the time to make two trips with the portable tank.