I have some data on the bridge.
Again it is a bridge high enough for the world's largest super tankers to pass underneath.
I am traveling east; I never take it west.
The Vincent Thomas Bridge in Los Angeles California, actually it may be San Pedro.
If interested I'm sure you could Google it and find the specs.
The beginning and end are approx the same elevation, a few feet above sea level.
I have been holding the speed at 45, up and down.
I have about 10 passes.

In EVERY pass the MPG at the top was 1.1 or 1.2 worse than at the approach.
In EVERY case the MPG returned exactly to what it was before the bridge when I reached the bottom of the other side.
Since the data is not varying after 10 passes I feel it is reliable.

The MPG numbers are in the range of 62MPG and the tripmeter had approx 28 miles on it.

I stll want to experiment with the driving with the load technique.
I respect those here with more experience than I, and impressive MPG numbers.

Also, this is just one bridge.
YMMV, with other hill situations.
But in this case the data supports the conservation of energy.
What you lose to gravity on the way up is recovered from gravity on the way down.

Need fewer troops to support.
Drive a hybrid.
Best tank 71.65 MPG.

Before this car I spent two years learning hypermiling on my 2004 HCH1.