This 2x 4 scheme has worked for me to carry 2 80 lb Grumman canoes. I think the Suburu should have 2 transport eyes each side front and rear (unless the've been removed) so tying stem lines should be easy and very secure.

: Cheapest and fastest route I can see would be to cut some lengths from a 2x4
: and secure them to your existing racks with stainless steel hose clamps,
: or some U bolts. You could make the racks 8 feet wide if you wanted, but
: it might be difficult to pass a semi .

: Bow and stern lines secured to the car at the bumpers or under the bumpers
: will keep the boats secure even on racks which are closely spaced. Many
: times there are rather random holes in the frame of a car. If you can find
: one in a convenient location, and get an eyebolt through it, you'll have a
: secure point to tie a rope to.

: Try something simple like this and do some slow-speed test drives around the
: neighborhood until you have confidence in the setup.

: Hope this helps.

: PGJ