Type in the difficulty minimum and maximum (must be numbers), and then press space to generate possible missions and their respective difficulties. Currently rethinking my choice of sharing this instead of placing it as one of my many Unshared But Quite Useful projects.
Hilariously inaccurate, but it'll give you slightly relevant difficulties for things below 10. Note that to use this, you'd best have already gone to orbit. Credit to Squad for their awesome game.