As the owner of two 40 yard bark blower trucks, I could post endless information about them on this forum. Considering they are a very specialized piece of equipment, I'd rather talk directly to guys interested in buying one by phone. Just PM me your contact.
I will post: if you are a capable business owner, but a smaller company, blower trucks will make you money.
Some of the biggest things you need to know, how to weld, diagnose, repair, motivate. Breakdowns on trucks are never ending. Motivations because the season is short in some areas and you'll work non stop.