Gary, you missed the WHOLE POINT of the OP.
( This is about brakes, not MPG! )

I can see where this is a case where you would have to rely almost 100% on the friction pads. But, #1 you said it was only ~2.5 miles. That is not very far... and not too much to worry about. #2 you are only going about 5 to 10 miles per hour. While constant dragging the brakes will get them hotter than you are used to, this is not nearly enough heat to warp the rotors or glaze the pads or cause damage.

Warping rotors and damaging pads occurs when the brakes are nearly hot enough to glow. This would happen driving down steep grades at high speeds for longer than 2.5 miles. ( Colorado Rocky Mt. Passes where there are steep paved roads, with higher speed limits, and still require braking... ) Ford has engineered for this second senario, with the engine compressional braking.

So in summary, at 10 MPH or less, you have little or zero regen brake.
At 10 MPH or less, you have basically zero engine compression brake.
At 10 MPH, it is perfectly O.K. to drag your brakes for 2.5 miles.

If you don't like the smell ( if there was a smell ) stop 1/2 way down for 5 minutes. That's enough of a rest for your brakes, although this is not necessary.
-John

P.S. And whatever you do, ignore any advice about "turning the key off" on steep dangerous roads with 600 foot cliffs!