Grouping by a calculated field

Hey folks,

Early stages.  I'm having a play around with ticket buyer loyalty, looking at...

1. Tenure: the number of years that they have been purchasing with us
2. Loyalty:  Number of years (seasons) within those bookends where they lapsed (didn't purchase)
3. Start and End years

I'd love to explore down into some of these categories but in order to do that I need to use some of these categories as rows.  Whilst I could pull the data out into excel (or SQL) and play, I'm just wondering if there is a way of row grouping these calculated fields.

Now that I'm writing this I'm thinking the only way will be creating Custom Categories and waiting overnight. 

Cheers,

Heath

PS: For the curious fields are 

• Tenure: [Max Season Fiscal Year]  -[Min Season Fiscal Year] +1
• Loyalty:  count([Season]) 
• Num seasons lapsed during tenure: [Max Season Fiscal Year]  -[Min Season Fiscal Year] +1 - [# of unique Season]
• Renewing Status: CASE
  WHEN ([Max Season Fiscal Year]) <= 2018 THEN 0
  WHEN ([Max Season Fiscal Year]) = 2019 THEN 2019
  ELSE 2020
  END