a little trick to make it keep in tune is to run pencil lead (graphite) or get some liquid graphite and put it where the string would lie in the nut, make sure your nut slots are big enough so the strings wont bind when movement is happening. if there is equal tension between the strings past the nut on the neck, and the strings over the fretboard - AND what theyre running over has the least amount of friction possible, then things would come back to tune naturally after a big drop.
another tip if there isnt any locking tuners on the neck: learn how to string a guitar properly!! a good guide on restringing is
here and i try get between 2 and 4 winds around the post as to not have too much shifting from the extra string.
another quick note - front mount locking tuners can be had, and one would just have to even out a flatter spot ( if it isnt flat already) from the nut and just butt it up agenst the fretboard then glue/screw it in and youre in buisness! if you do do that, dont forget a string tree that goes right behind the nut! if you dont have that then everything will go sharp once you lock down the strings
hope i helped!