So, on one of my visits to the FLAPS, I discovered what I think to be
the perfect straps for Westy folk. ROK Straps makes a variety of
straps, The ones I like are the all purpose adjustable ones. They come
in a variety of lengths (I have the 10 foot ones)

The hooks fit under the tie downs on the Westy carrier, they have a
quick disconnect and aren't terribly expensive (I got the 10 foot
package with two straps for $15).

www.rokstraps.com