Calculating the drag-related weight transfer is relatively simple if a couple quantities are known or can be estimated. dW = (D*h)/WB where dW is the weight transfer (lb), D is the drag force (lb), h is the height of the center of pressure above the ground, and WB is the wheelbase. h and WB should have the same units, e.g. inches, feet, or whatever.
By way of illustration, assuming drag of 1600 lbs, h of 20”, and a wheelbase of 80”, the front end will get 400 lbs lighter and the rear 400 lbs heavier. Perhaps not a big effect, but at least accounting for it would get the traction calculation that much closer to reality.
As regards a front-drive roadster, this weight transfer would eventually limit the speed achieveable since traction required is increasing in order to overcome the increasing drag, but the traction available is decreasing as the drive axle weight is decreasing. Such a roadster would probably be inherently front-heavy, and the limit may be beyond the power available, but in any case, the remedy is straightforward--ballast up the front or induce some aero downforce. And, adding ballast to the front is much more friendly to aerodynamic stability than having to add it to the rear.