It seems to me that the main objection to deadbeating is the advantage gained from double/triple army deployment when the deadbeater resumes the game.
My apologies if this has been suggested before.
When a player "Misses a turn" simply allocate 3 (and only 3) armies, regardless of bonus entitlement, to that players territories in a random fashion (ie NOT all on the one Territory unless thats all the player has).
A penalty is thereby imposed on someone who is simply using the missed turn as a tactic - AND the person who missed due to a death in the family OR my internet connection broke OR I had to work late OR My significant other made me do chores instead OR My big Sister wouldn't let me use the computer etc etc etc etc etc ad nauseum - will still get some value added to their neglected game.
Plus all the active players are able to adjust offence/defence without trying to second guess where a returning deadbeater might deploy a potentially overwhelming force.