well I dont think sleeping in your truck will be necessary.
First thing to do is to go to:
www.gencon.comthere be sure and register so you can get your Rubi system number.
This number will help you pre-purchase tickets, your four day badge and can help with getting your hotel room.
IF you have a ton of trouble with your hotel room, be sure and check at Gamers we have a forum dedicated every year to gencon.
People have been able to get to know each other and even become weekend bunkmates when necessary.
Taking away the badge cost and hotel cost I would suggest to you budgeting about $400 for the weekend. You can pretty much eat on the cheap there. You will need money for the events (if you did not pre-puchase your tickets) and the vendors hall always has amazing deals that will rock your world.
IF you come on Weds say around 4 pm EST.... plan on meeting up with all of us (it has become a tradition) for dinner and then we usually go RPG for the evening and just have a great time.
I must say if you do anything make sure you prepurchase your badge. The last thing on earth you want to be doing is standing in line on Thursday morning for the badge. When I say LINE I MEAN LINE!!!!
it is not hard to navigate your way around and have a great time. By the way dont plan on getting a ton of sleep either..... it just isnt going to happen.