Definitely consider Hofstadter's law in this project:

Hofstadter's Law: it always takes longer than you expect, even when you take into account Hofstadter's Law.

You can make an aviation corollary to this law by replacing "takes longer" with "costs more".

Seriously, I think a manned option might be cheaper, quicker, and more flexible in terms of accessible airspace (not saying this just because I make a living flying airplanes). I do suspect the manned option might be more administratively burdonesome (getting your payload approved for wing mounting) and less fun.