The opening doors for sure violate the smooth air flow when underway.
Consider it to be a speed brake and all is swell.
Remember it is going to take power to do that and consider where it is always going to come from with out fail.
With a suitable linkage, all of the considerations mentioned for holding them open can be accomplished with the energy you have available from the pulling forces on the lanyard after it is deployed.
If the proper anchor height is buried within the doors you have to consider what a side load is going to do.
Unlike a relatively short vehicle that can sometimes be saved from a spin with the pull from the chute, a proper balanced and aero package will try to straighten out on it's own if the human error is just removed from the problem.
The human failure has the tendency to pull the slowing chute too late into a sideways adventure to bring it back into line smoothly.
If the doors are going to act as a speed brake in any case, remember the air flow is on all sides.
If the hinge action opened them up and down, the lanyard would be much more able to move side to side (cross wind) without hitting the hatches.
The hatches can also be made to open wider with the pull from the lanyard if they don't have to fight limit stops without damage if required
If the chute goes way up and down, that usually means the vehicle has lost contact with the ground and the health of the doors is of little concern.
Bike liners have a required automatic deployment feature when the ride angle is beyond normal limits and a car might do well to consider it.
Build it like you are going 100mph faster than you ever will and you can call it the "COMFORT ZONE".