The more I think about it, this would make the game more strategic too. They could increase party size to 6, but if you have 6, camp supplies cost will be more for short rests. 6x4=24 supplies for each short rest. Suddenly, camp supplies are WAY more important and limiting short rests so they aren't abused. Now, it becomes strategy. Do you take 4 or 6 party members. The more you take, the more supplies you need but the more strength you possess in combat.
Not enough supplies, half healing per short rest. Still can do it, but less benefit. Less than half supplies needed, no rest at all available. Suddenly, camp supplies will need to be conserved a whole lot more.
