I do the same thing, except alone and no girls.
Once on the truck, two straps only, on the bars.
Hi. For Windmill cycles and my self bought and loaded over 2500 bikes. Loaded them in open trailets pick up beds inclosed trailers. I would always ride them up the ramps I will all was use 6 or more straps. I have had 5 bikes in a Sprinter tall and long van. I have had 12 bikes in a 32 ft inclosed trailer + 2 in the open bed of the pick up truck Dodge 3500 or a Chrevy 3500. We also sold cars so we had an open car and the 32 ft inclosed. The Chevy pull better loaded with the 32 footer than The Dodge pulled it enpty.