I believe what Firko and a couple of others are saying, but at the same time what they 'are saying is' here are the problems, logistics, how can this problem be solved?
A problem can be looked at in many ways as we all know, so it just depends on how big or small you want the problem to be.
Logistics can be solved, lets look at the big, grand, all out style this event could be (if thats what you want) with corporate sponsored 20ft shipping containers (3 of) signwritten up for advertising. Bike and gear movement now becomes a less costly and time consuming affair. Riders and supporters fly in to and out of the two furthest meetings.
If that all sounds to hard then it looks like a long drive with a couple of good vmx mates.
The cost factor for a Tri-series needn't be looked at individually, it could be collectively riders, clubs and sponsors, with a little forethought of who is willing to go to such an event, money could be raised via raffles or other such ways. The 'state club' could be allocated 'x' number of bikes to go in their container for their 'State Champions' and the rest of the room in the container go to their club members.
With spots up for grabs at state champs, this could mean more riders could turn up to race at state champs??
A Tri-series could be a great thing for vmx and yes there will be alot of time, effort and organisation at the start but if done correctly and well thoughtout from the get-go, then riders will want to go.
A three way Tri-series doesnt just have to be about the individual rider, as it could also include teams racing with riders riding for their own club.
I say good luck and dont put a time frame to have it up and runnng by until you know exactly what you want and how you need to have it run.