That does seem to be an important thought...creating some compelling reason for him to talk with you again after this shadow work.

One that worked for me was to listen carefully for some opportunity where I could help. Like, "it sounds like you're negotiating with Microsoft... I just finished doing that with another company, there may be some helpful things I could share..."

Something like that creates a basis for an ongoing relationship. Such that you don't have to try to press a sales pitch in a hurry.