7 miles from property line is totally different than 7 miles from the Magic Kingdom.
On a cab ride I took two years ago, was 6 miles, and nearly $20. I know there are no resorts that close to the Magic Kingdom outside the property.
I would really rethink your idea on a taxi ride, unless you have money to spend. The Lynx bus system is quite nice and there's a pick up at the Ticket and Transportation Center (TTC). As long as your hotel is along Palm Pkwy or 192.