When i got to much offspring, i raise some froglets in the plastic storage boxes.
I just make a hole on both sides and cover it by glueing very fine mesh on it.
For the offspring i use a lot of leaflitter so they can hide and forage for food between it.
Never have problems opening the top lid, they just go on with their bussiness or dive between the leaves.
I think it is not the best idea using a curver box for housing a frog permenantly,
you are better of getting a viv for that.
Looking trough the sides of a plastic container gives far less vissibility anyways