I dont think you need dust covers on the Front USB port. The inside of my car is as clean, or cleaner than my office!
Also, i would be happy to buy a unit with a MINI USB port on the front, and use an adapter to plug my thumb drive into it. This is because 95% of the time i wouldnt have anything plugged in the front, and that space can be better utilised.
Great work, i dont know weather to buy a LCD to finish my carputer project, or wait till June!