Use regression discontinuity for assessing marketing campaign performance

I had this idea the other day, dunno if its been done before:
Say you want to know how effective your marketing campaign is for VIP customers. However, marketing won’t let you randomly assign VIPs to ‘gets campaign’ or ‘doesn’t get campaign’ for a true AB test. What do you do?
Well, if VIPs get the marketing campaign and non VIPs don’t, naively you could compare VIPs to non VIPs to estimate the effect of the campaign. The problem is …

campaign datascience discontinuity marketing performance regression