I have been riding about 14 years and STILL have this habit. I was taught to ride like that as well, and was never corrected by any Trainer I've had in the past I don't know how many years.
So I am right there with you... trying to get my inner calf on the horse.
I just try to concentrate on my legs during riding, keeping and holding the right position. When they are in the right position, you will feel the difference. At least, I do. It brings my seat more forward and I can actually feel my hip rotate and my legs hug my horses sides better. It will help give you a more stable seat as well.
Practice makes perfect!
And really your toes aren't that bad, and no I don't suggest tying any part of your body while riding, let alone your feet. Not safe, you are 100% correct. :)
...he's so kissable, huggable, loveable, unbelievable...