Advice needed: bodywork techniques. Or, learn me sanding curves

So, many of you all know im shiny happy person deep in rebuilding the challenge miata from a bare shell up. Its the curviest car ive ever done bodywork to, and im trying my darnedest to make it flawless. 

Which brings me to blocking it. 

Im about halfway through the first round of filler covered in a heavy two coats of high build, and im using 320 grit on a 12 inch durablok and a hard 3x5 foam pad. 

Im doing my best to get everything with the durablock, but theres more curve that it will flex in many areas, and the sharp compound roll from horizontal to vertical portions is a bear as well. Im finding myself grabbing the little foam thing to get many of these areas, which in my mind will lead to a wavy surface when the clear and buffing is applied. 

Whats the technique/feel/trick/tool/wisdom im missing here? 

Picture, because we all like pictures. 

I know you go opposite what you think.  I don't know how to express what I mean, but basically you sand the curved parts with the sander always tangential to the curve.

I love the Durablock collection and do 80% of all sanding with them, but have a box full of weird shaped foam toys. Yeah I know what image that conjures!

Pool noodles come in handy. Pipe insulation with rubber hoses of various durometers  in the middle can be handy. I use the dish-washing  sponge pads with the scotch-brite on one  for close quarters like the nose of the P1800 or other close curvy areas; I dont use the scotch-brite surface to sand, I put the sandpaer over it so it is just a soft sanding block. Golden rule is "no fingers on the back of the sandpaper". I have been known ot roll up a scotchbrite pad into a cylinder and then wrap sandpaer around that.

The other unfortunate secret to a perfect surface is to not try and stretch the life of the sandpaper. Dull paper makes low  frequency waves. You can feel when sandpaper stops biting and then it is time to grab another piece. 

This game can, and will, drive you nuts.

so, the sharp roll from horizontal to vertical: ive been using the 12 inch durablok going in an up and down and x pattern across it. However, looking at the "high spot" pattern that appears in both fenders im either hitting stamping waves or doing something wrong. Thoughts? Also, at about center of the tire i switch the the foam pad because the curve gets to sharp. Will this be seen?

On the rear quarters, similar thing and same motions. If you look at the picture, you'll see a distinct line of high spot. 

A picture of the curve in guidecoat to help you see what im working with 

And the blocks ive been using 

You are correct. I see a series of white dots that indicate high spots. What is the white coating layer?

I see panel work that needs to be done, not a sanding technique that needs improving. I don't know about the rear, ( unless new quarter panel was stitched in) but the front looks like someone drove the car without fender liners and pebbled the fender from below. Time to tap those suckers down then spray more high-build. What are you using for high build primer?

The white coating is epoxy primer from where it was bare metal. I'm using Upol high build.

The rear has not had quarters put on it and the car has never had any metal work other than seeing welding that I know of. I had to do a lot of straightening to the driver's rear quarter and there's still some more filler work to do there.