The difficulty in applying a punishment to a user that camps, is that everybody seems to interpret the definition of camping differently. For me personally, camping is the act of isolating oneself from the opposition and refusing to engage in any form of combat, whilst not complying with the objective.
For example, to some, camping in Eggwars is a matter of staying on your island with a Punch I bow. To me however, that is not camping as you are only doing what the objective tells you to do; to protect your egg.
Because of this, camping should not be punishable, but rather should be made more difficult to do. This can be done by implementing degradation of the map as you have suggested, however I feel as though the majority of players will vote against its use in Skywars, as it was initially removed from the server due to the community's dislike towards it.