I have experience with this and I'll just say it's a challenge no matter what! But totally agree that Daniel's ideas are spot on. I've been fortunate to work for companies where Pub Sector is a big priority so they actually have an event similar to the main US event but its a Gov version so it was a lot easier to convince them to speak and be engaged. Def speaking is a great way to build the relationship and eventually get permission for a case study, video, etc. At the end of the day, some just won't be able to get permission, but we had a lot of success w/ SLED because of relationships and having advocates who had enough clout within their org they could get it through. They really saw us as a technology partner, not just a vendor, which made all the difference.