I have walked the coastline of Great Britain with my dog Havoc,Nov 2006 - Oct 2007. Aprox 5,000 miles. we carried everything on our backs, tent, sleeping bag etc. We did average of 18 miles a day. 26 was probably the longest day.
Carrying 40lb on your back certainly slows you down - so i think 30 miles a day is being very optomistic. Also you need to be able to enjoy your challenge.