LF,
I've done near north east to west to south west and back again in 7 days, so I would say 3 days is plenty if the purpose of this trip is flying rather than visiting the places en-route. And let's face it, the route you'd naturally take is deathly dull once you're east of Colorado. If you've got extra time you could have a lot more fun with it.
I might have been interested but I think your numbers are all a bit screwy. In my experience the hotels closest to the airfields are not $40 a night and besides, I wouldn't choose to stay in them and would rather enjoy some luxury. But more important than that, in my mind, this is clearly a positioning flight for your own aircraft, so don't you think you've got a bit of a cheek asking for half the costs? Of course, you can ask for what the hell you like - it's your trip and your aeroplane - but personally it puts me off.