The Mike Leonard event is great, 6 hours racing non stop, you never stop doing something either racing or helping your team.
It works that your team marshalls your cars and sometimes other teams help by moving you further away from your marshall
Its all a great day and for a annual thing its definately worth doing and is a really good day and for a good cause.
Different to what your proposing though as you do as long as you can which usually is 6 or 7 minutes and then you just switch with a team member, stick a battery in and wait till its your turn again. I think 6 hours with one car would be rough on it lol, i guess with brushless though it should be oaky but I wonder if it would last that time without thermalling