Not an easy question to answer. I have attended but am not part of the team hosting this gathering.
A) Are you likely to only want to look at the trucks all lined up outside the park store and switch back to your Norris Lake activities?
B) Or are you likely to join in all day with the event team and take part in the evening activities?
If you align with A, then registering would be a generous step to take. If you align with B, registering would probably be an appropriate step to take.
In the end, you are the best judge because it is unlikely that anyone would say anything.
In prior years, the team hosting this event has emphasized enabling an atmosphere where everyone can have a good time while getting to know one another and their Cruisers. Starting last year, the objective of raising funds for ALS research and awareness was added as a clear objectives for the event. This is a consideration that also weighs on the registration criteria.
I hope this is helpful.