Why is it pompous to write Op. XXX ??
It is just a way to catalogue something, it should not even be outdated or old fashioned.
With it you're not stating "I'm the best of the best and everybody else is under me"!
(Unless you really write it next to ALL your opus numbers :P ), and using just the date of composition, either begin or completion of your work, doesn't make you more humble and "human", it is just about what works for you or not.
For the help idea I think that you should just do a main list of your works, for those you've finished and you give to them the opus number and maybe also the date you started or finished it, and for the ones you've not finished you do the same thing by putting the opus number and the date of beginning, so you always know when you did it, and what number it is and the title, if ever...
Always if you like to have everything in order and catalogued...