Painting a full truck in the garage is seldom a pristine operation. In the past I have used a few furnace filters in the windows and a row of box fans under the garage door just to get some good flow along with wetting down the garage floor good and I still ended up with dust. But I do enjoy doing some smaller parts in B/C in the garage...
Your thought on laying down several layers of paint then sanding flat/smooth will probably yield the best results given the color you are using. I assume you have a good buffer? Another option would be to shoot all the individual sections, wet sand smooth, assemble, then lay down a good clearcoatover the entire truck. Of course, that would mean a lot of extra taping and papering but your time is free where as a commercial painter does not have that luxury.