It can be tricky, I have experienced it too. First solution is that the handle is still available even if it is obscured. If you place the curser over where a handle should be it will pop up red and be available for clicking and using for resizing. This is useful if most of the resize box is visible and you can judge from the bounding edges where the obscured handle should be. But this can also sometimes leave one fishing around hunting for the invisible handle which can be frustrating.
Second solution is to set up a keyboard toggle for x-ray face style, which when switched on shows all handles through surfaces.