With the stock alternator , no chance , at idle few will make 50A , and 50 x 13 (charge voltage ) isn't even 700w.
The fuel burn of the slow running engine with a big 200A+ alt and very pricy inverter would be far higher and louder than would be acceptable.
A 2000W or 3000AW Honda would be the choice for 120V service power.
Making stuff , hamburgers hot dogs will put youi at the mercy of both the US CG and the local resturant laws.
Just selling stuff , that someone else made is far easier.
A fellow at Block Island seems to do well (for about 20 years) delivering the NY Times , Bagles , milk , and other breakfast stuff on Sundays.