Alone is very different. I wouldn't recommend a job like this for a one man shop. Even if you could do four a day, you'd be looking at eight weeks of doing nothing but these vans. That'd be sure to piss off every other customer you have. Not a good thing, unless you'd like to make $35k over the next two months. If you can handle your other clients, that's a handsome profit for a one-man shop.
On the other hand, a company like ours would take on this job, have a couple of our installers knock it out and make a nice profit. All while keeping our other clients very happy. These fleet jobs are not for everyone, but if one-man shops want to compete for them, they have to be willing to do so on the level that these jobs go for.