Setup questions for sewing cordura cusions on a Pfaff 145

[barrys]

I've already asked about this in some posts a while back and bobbin replied with tons of useful info.  Just wanted to make sure I had it all correct...
I want to sew some large cusions with welted edges and a zipper out of Cordura just because I have the cordura (would use Phifertex or Sunbrella if I was shopping fresh).
I wanted to know if this setup is OK:
#18 needle.
#92 Star Ultra-Dee thread.
"Presser" style foot where possible -- will be using the welt foot a lot though too as required.
Tension way low -- upper and lower.
Presser foot pressure backed way off.

Does that sound OK?

[sofadoc]

That #18 needle might be a little flimsy. You can always move up a size if the thread is breaking. But I don't do much Sunbrella type stuff. If that's what bobbin said before, I'm sure it's right.

[barrys]

This was the thread with Bobbin's comments:
http://get-up-and-go.com/upholstery-forum/index.php?topic=7043.0
I need to follow up on that advice -- especially the stuff about adjusting the tension on the bias. 
But, there was no recommendation on needle or thread.

In another thread, Mike802 recommended 17 needles with #69 thread.  That would probably work well, but I have neither of those.

So, I have 18-24 needles and 92 thread.  I was just guessing that the thinner needle would be a little easier on the lightweight cordura.  Maybe I'll try 20.  I don't have a lot of extra fabric so I can't experiment with a sample cushion or anything.