Kanban Style Work Items

Right now we’re using a board to track all of our engineers specific work items through a Kanban process, moving each item along the swim lanes until it’s “Done”. That Done column figures to get pretty large after a while and I’m looking for a good way to limit it, but every solution I find runs into a different problem. Any help/feedback would be appreciated. Here are the methods I’ve tried and the problem associated with it:

  1. Archive after it’s been in the status for X days - Once an item is archived, it doesn’t show up in reporting anymore. We’d like to still be able to report on some statistics well into the future for the type of work that’s being completed so this isn’t a good solution.

  2. Move the item to an “Archived” board after it’s been Done for X days - This seemed like the most logical next choice on how to do this. It seemed to be working until I was mapping the item into the new board and ran into a big problem. My tag column doesn’t map. It looks like it’s not supported at all. We use the tag column to track which client we’re doing work for so we can utilize the universal search for other work related to that client at a high level.

These seem like common problems so I’m hoping I’m just missing some easy solution! Please help!