**Having a part time team member is probably a bad idea.**
When something needs doing that can't be done in the slice of their time you've been allocated, that is waste. When you have to train and familiarize them to the level of a full time member and then can't get full time work out them, that is waste. When they have to catch up after missing a couple of days: waste. _Et cetera_.
**Leave the board as it is.** Part of the reason you have a board is to help you identify process improvement. You're uncomfortable because your board is working correctly.