If you think carefully about the geometry of your bike and your legs, you will realize that the distance from the pedal to your arse will be the same on any bike set up for you, regardless of frame size. The height of the bottom bracket generally is not changed from one size frame to another, and you should have the saddle height adjusted the same on any bike, so the distance from saddle to ground should not change.
There are comfort bikes designed to put your feet flat on the ground - these are called 'crank forward' bikes, and they do get your feet comfortably on the ground when you want to stop, but they put you in a less efficient pedalling position.
You may have misunderstood what you read (or read it from a less-than-accurate source) about your toes touching the ground. I have never heard or read anywhere that you should stay in the saddle when stopped, but have heard (and read, and said) that if you stay in the saddle when stopped, you should only be able to touch the ground with your toes. They are not saying you should stay in the saddle when stopped..
The correct answer is to slide forward off the saddle when stopping. If the top tube is uncomfortably contacting your crotchular region, then keep one foot on a pedal and lean the bike over towards the foot you are putting on the ground.