"...and a serious amount of math work to get your position within a couple of miles"
Nothing you can't put on a programmable scientific calculator. There are power series on the orbital elements for the positions of the Sun and Moon up to navigational accuracy for a couple of years either side of now that can be downloaded into a modest calculator along with positions of the navigational stars. Coordinate transformations are relatively routine.
Coat: Mine's the one with the Ebco emergency sextant in the (large) pocket.