Simply solution would have party size limit as part of the difficulty settings.
This touches on something I've always wanted in games. On top of difficulty with number of mobs and power/intelligence of the enemy why not allow people to determine difficulty based on their power setup.
* Partly Limit
* experience multiplier (lets level go above 12)
* Starting Stats in Character Creation - 8 in everything harder difficulty score and 30 in everything lower difficulty score.
* Buffs/proficiency etc. - Want to start with no proficiency or all? Want to start with few feats at the start or none
You could do this on so many fields allowing for a difficulty sores that players could change as they saw fit. Can you imagine trying to pet it with a 2 party limit and starting with 8 to all states. Just putting this stuff on a slider would open up so many replays of the game from the crazy challenge to the god speed run.
