mjbow2
Thanks for the link to the article.
I can guarantee there are BBJs under Part 91. There are many with only 19 seats (certified for takeoff and landing), or where the weight and balance manual is changed to limit the payload below 6000 lbs – there is an FAA document that OKs doing it.
Boeing also has a document comparing Part 125 to Part 91 for prospective BBJ buyers.
With regards to letters of deviation from Part 125, there is an FAA internal memo trying to end the party on that one – the FAA is suggesting there is no point in Part 125 if they waive everything down to Part 91 standards – the final letter depends on each FSDO: sometimes you can strike gold and other times hit bedrock. They no longer issue full deviations from Part 125; you have to request a deviation from each sub-part and they are not easy to get anymore.