I voted 'other' and here's my strategy:
Don't decide today what you're going to do in three weeks. Let Edwards play until Boom is healthy. then, whoever is the better LG just put them at LG.
If that's Boom then the Rams just go back to status quo.
If that's Edwards then give him the job. I don't see any reason to do anything other than giving yourself the best chance to win every game this year, even if it means Boom is 'just' the swing tackle.
I get that having Boom on the field this year at LG would benefit him next year, but if McVay follows his one-game-at-a-time approach then he ought to do whatever he can to win the game at hand. If starting Edwards over Boom does that, then do it.
As to Boom's development: have him focus the rest of the year on his LT responsibilities, take the first team reps at LT once a week when Whit gets his vet days off, and if the right opportunity arises have him play some LT in real game(s).
AlbaNY_Ram