I think the actual mileage from Itasca to Mile -0 is 2340 miles etc.
There are about 4 groups of people paddling the whole thing this summer.
I highly suggest you get on facebook and friend the two groups
"Mississippi River Paddlers" and "Lower Mississippi Paddlers" About 20 + people on there that have done the whole thing.
I think 30-45 a day is a lot but doable. My friend Bob Bradford went from Itasca to Mile zero for a world record in 18-days!!! Contact the two groups to get the times what the last 30 people whove done it have done it in
Also google "Quawpaw Canoe Company" and John Ruskey....he knows more about the lower miss than any person.
Also Mike Clark with Big Muddy Adventures out of st louis
a wealth of information.
A girl is doing the whole river solo this summer in a cataraft. you can find her blog on the face book page.