Could you post a picture of the room - from the inside. Hard to give advice.

Sales guy obviously is giving bad advice because of door.

I took a second look at your drawing, Are the blinds going to be an outside bracket, that is outside the window frames opposed to inside? If so you will have a little bit better chance of it working out.

Yes, they are outside the window frames. We're building a false wall above top windows so shade concealed there.

Here's a picture from inside. Doors not yet installed but will be any day now (!) I mocked up how they will be, 5 ft by 8 ft. doors.

Don't forget that in 13 feet - if the shade isn't exactly square and level, it will be slightly crooked in the frame. Just a small amount - 1/64" could be an inch in error.

You might need a laser to install them.

Another issue is the window openings are not always square, you can install the headrail perfectly level but if the windows are not square well that's one of the rubs.

One thing that could be done is to make a "T" (say a 1x1 - covered by a 1 x 2). between each window. This would give you 1/4" over the edge of the shade. But it looks like that's not possible now.

This drawing is looking down on the window. The red - is the "T" I'm referring to

Great ideas, all. We will use laser and try to ensure windows installed squarely. We can consider geoffrey_b's idea, too or something similar. The motors are a must; that wall has 10 5' x 8' patio doors, not counting windows...so @ 500 sq ft of glass without any useful overhang facing due west. This is the way it was planned but sun protection a must and automation a must.

Here is our take on it...cheap roller shades will not roll up the full length in a straight way - but the more expensive ones do. Roller shades have up to 1 inch in gap on each side anyway, this can take care of a small adjustment. As previous professionals mentioned: don't use a battery motor - it is to slow, to waek and you have to replace the batteries quite often for this length. Use 3 motors, even if they all run (and they will) on a different speed. You can set different stops for the blinds for example at 1/4 or 3/4 and they will all stop at the same position even they motors are different in speed. Nobody though has mentioned the fabric yet - this is crucial because there is quite a weight at the end. Make sure the fabric is suited and warrantied by the manufacturer for this length.

Good Luck on your project!

We also ended up doing something sort of attractive, I hope...putting rollers inside their own part of the wall so they aren't visible. In other words, a part of the wall (false wall) that comes out about 5 inches above doors and then rollers and motors hidden inside false wall.