Simple if you follow set format. Some shots will be upright, by that I mean the camera on its side, others will be horizontal.
The trick is to do all uprights in one run then all horizontals in the next, change the film in the turn.
Hellicoptors whilst very easy to manipulate position are 1) very noisey 2) can cause other probs like camera shake due to vibration ( so ive been told, never tried) 3) very expensive, they are maybe more suited to landscape /scenery type of work all depends on the type of work you want to do.
selling will be the hardest part, competition, low percentage of film makes a sale.