I have no experience with the Looksha, but I do have a Santa Cruze also from
Necky. I use the Hullraiser with no problems. The kayak was secure when
strapped in and I also used bow and stern tie downs as well. Since you have
a Thule system, I assume you are actually using the hullaport, not
hullraiser, but I guess the setup is the same. The plastic on my Stana
Cruze was stiff enough, maybe the Looksha is thinner? Perhaps someone else
has a better answer, but you may be strapping it in too tight.

Robert