Adding propeller blur - how about this?

I recently got some promising picture of the Battle of Brittain memorial flight event at Ladybower dam, but being old and wobbly and using  the camera hand held (7D with 400mm F5.6 prime lens) I have to use a high shutter speed, which of course freezes the prop motion.

I've found quite a few guides to doing this, but they give pretty poor results against a landscape background (rather than sky which is more forgiving)  and generally also only work head on, so I have been trying to find a better way to do it.

Below is an outline of the technique that works for head on to about 45degrees.  Can I improve on this to either get better results, or to get there more easily?

Here is a sample I've been working on...  http://www.flickr.com/photos/pootles_place/9143663056/in/photostream/ with one done, one in progress and 1 original.

1. open image in CS
2. copy into new layer - name it props-gone and remove the propeller - you can leave the boss behind but all else should go.  you may need to refer to other similar images to put back some of the missing bits.
3. copy the original layer again and rename it props blurred (maybe even do 1 layer for each prop on multi engined planes).
4. mask out everything except the blades and the boss. make the selection of the blades in particular just inside the blade edge, rather than including anything beyond
5. If the prop was not at or very close to head on, stretch the image carefully so the prop would form a circular image - note how you got there as you need to reverse this later.
6. turn the mask into a selection. and create a new layer from this.
7. working on the new layer, add a tiny bit of something to the selection so that when you use transform, the centre of the prop will be the centre of rotation. The transform area needs to be a square exactly centered on the centre of the prop / boss.
8. ( I did try various ways of using radial blur at this stage, but it always left the mask unchanged so was actually any use)
9. now copy and paste in place the selection, and rotate a few degrees ( all parts of the prop need to overlap, except perhaps the very tips of the blades)
10. repeat this several time to build a solid prop image - this will look silly at this stage, because leading or trailing edge highlights will be very obvious!  This will also update the mask so the new bits are uncluded.
11. now make a selection that includes all the blade bits except the very leading and trailing edge, and goes slightly beyond the blade tips.
12. use radial blur at fairly low angle to blur out all the leading or trailing edge bits within the blur area.  If the boss has very strong markings you may need to tweak this separately .
13. if you had to stretch the prop back at step 5, now you need to do a squash to get back to then right eliptical shape
14. turn off the original prop cut-out layer.
15. now make sure the blurred prop is on top of the propless copy of the original and turn down the opacity to achieve an appropriate result.