Guys - I have a toyota tundra. Just put Yakima rack on the truck cap. Putting two SOT yaks on the roof rack upside down... question is since the racks don't come over the windshield, I'm I safe with just two straps over the yak and around the bars? Or do I need to use bow and stern straps also? I've gone on close to home trips with just the two straps without problem but planning a 7 hour trip at highway speeds in the next week. Thanks!