3.3V @ 10mA from 5V - 35V
Use a linear regulator that can handle 5V to 35V input. It outputs 3.3V.

It is that simple. You can use a buck regulator, if efficiency is an issue. but 10mA at a 35V drop is still only a 350mW dissipation.

I suggest the linear, keep components/complexity/noise down.