Software for estimating Frontal Area

yup. walmort sells the software for $2
ILL has the other pack

If you're will to play with .NET, it's not so hard:

Use MS Paint to trace the subject (using white) in a picture with a
control item (10cm x 10cm white square) above/side of the rider.

Turn the picture attributes to B&W in Paint.

Split the subject picture and the control item into two separate images
(each of the same size as the original, but just make them separate).

Turn the exterior of the Rider outline to white (rider be the only
thing black). Do the same for the Control square. Invert the colors
of the control (so the white square is black now, just like the rider
in his image).

Evaluate each image with this code:

System.Drawing.Bitmap image = new Bitmap("image.jpg"😉;

int height = image.Height;
int width = image.Width;
int pixelCount = 0;
int totalPixels = 0;

for (int x = 0; x < width; x++)
{
for (int y = 0; y < height; y++)
{
System.Drawing.Color color = image.GetPixel(x, y);

if (color == System.Drawing.Color.White)
{
pixelCount++;
}
}
totalPixels++;
}

You should be able to get the pixel count for each object. Using the
control 10cm by 10cm, you should be able to determine the size of each
pixel on the rider and get a pretty decent (if not consistent) estimate
of frontal area.

You could package all this into an app and do all the editing there,
but that would take more time. Certainly doable though (especially if
you use the TabletPC Toolkit which does much of this under the sheet
using the Ink object).