Rather than trying to zoom while holding the mouse button down for a selection, I find the best option is to select what you can and let go. Then zoom in, hold the Shift key down to add to the current selection and continue drawing your selection.
Basically, a selections does not need to be made in a single drag of the mouse. Your'e free to let go of the mouse, hold Shift or Option/Alt and add to or subtract from the part of the selection you already have drawn. Or even enter Quick Mask Mode to use a brush to alter the part of the selection already made.
Actually, learning to let go of the mouse at times is very beneficial. It provides history states allowing you to undo when you accidentally make a misstep. This way, rather than spending 30 minutes to get a selection correct and then you falter - having to do it all over again. You could spend 10 minutes, let go, and repeat. That way you only ever have to start from a partial selection rather than doing the entire thing again.