I had some troubles this summer when transporting my canoe on a rooftop foam block kit. This was during very strong crosswinds (35+ mph) and it twice made the canoe come off the blocks. I was wondering if this was because the foam block kit wasn't a good one or because my securing technique. I followed all the articles and never had problems except two times in bad winds. I've never had issue when transporting on a rack, just the foam blocks. I want to go back to not having a car, which means foam blocks on a rental car or a friend's car, but concerned I won't be able to safely transport on foam blocks. Are strong winds an issue on foam block kits ?