I think the number is not important, but what is important is to show what your willing to do to get business for your company. If he has 5 installs set already, I would think that should at least cover his flight and hotel. When you make an effort to show a club community of this size to what extent you'll go will be rewarded in the long run, trust me.
For example, my brother and I run a locksmith business and when we started we sat at a radio charity event once and did nothing but cut keys for people all day long. We ended up burning about $200.00 worth of keys and a whole days worth of potential business. It paid off because we got a $2500 lock order the next day from a businessman who built a new warehouse in the area and needed to put quality locks on it and was impressed that we took the time to do this charity function. He has been a customer of ours for 13 years now with another 7 warehouses and plus we do all his automotive keys for his delivery vehicles.
I have no idea what Steve makes per install or how much time it takes to put one in, but I find it pretty hard to believe that he would even have the time to install 15 or 16 cruise controls in 2 1/2 days. But I could be wrong.