Add a feeding bowl made out of glass and it'll solve your problem with the feeding. The crickets can't get out, the frogs will very soon learn where the food is, and you can easily monitor how much they eat. You can even add two bowls, if one frog is hogging all the food. A 15 gallon is ok for 2 froglets, but I personally would upgrade when they get to adulthood and larger.
Red eyes rarely overfeed, as the seem to regulate their food intake (unlike White's).

Good luck!

EDIT: Got ninjad, hard...