[lunarhighway]

it's not a stupid idea but it's a little outdated in terms of technology i think.
it would be cheaper and more reliable read out the vehicles speed and have a stepped motor actuate whatever dam or skirt you want to move.

not saying something like that wouldn't take a lot of knowledge and still but i think in the end it would work more reliable than a spring operated mechanical version.
if you would really push this idea (in theory it's perfecly possible to build the folowing today) you could include a manual override and storte this info and link this up to a GPS

for example this would allow you to take certaing obstacles at higher speed and the dams would raise and lower at that spot regardless of speed on other places like when coastig to a stop you could force the vehicle to stay lowered to extend your glide.

on the other hand you could just construct the skirts from a flexible material and use springs to balance it in the right position