I'm looking at at an 8 Channel CCTV dvr for about 175.00 bucks. Then plug that into a wirelss router (about 35.00 bucks) to broadcast to the Ipad. Infrared cameras ar anywhere between 20 and 50 bucks a peiece, depending on the waterproofness and resolution. With an 8 channel system, you can position cameras front, rear, in front of tires, underneathe the drive train..... anywhere you want to self spot. You can also get 4, 12 ,and 16 channel DVRs depending on your needs and budget. I do not believe that the size of the Hard drive of the DVR is really that important, because I wouldn't be running it all teh time, just for a few hours at a time.
Right now its in the brainstorming stages. If and when I do it, I'll post a full write up.
BTW, any input would be greatly appreciated.