I had to look up what a Yakima Lockjaw is and I see it's just like my roof racks, upright, no tire removal, I love my racks. You are talking about welding a hitch mount frame (like your hitch haul) and attaching the Lockjaw(s) on it. Sounds like a perfectly fine idea to me, they already make hitch bike mounts just like that and they work great.
My brother-in-law has fork mount and/or upright mount bike holders on the roof of his lifted Suzuki XL7 suv, my sister called yesterday to tell me that mom and dad's driveway is no longer safe for roof mounted bikes. :shock: They pulled into the driveway and took out the cable which messed up a bike and possibly the rack, I couldn't get the whole story as she called when I was driving around a group of my students doing a video scavenger hunt.
The power lines over their driveway have always been a concern for big vehicles (dump trucks and their ilk) but the last 2 times I've gone up the driveway with big bikes on the roof (mountain bikes and then cruiser) I have driven slow and looked out the sun roof and had room to spare, of course a lifted XL7 is quite talled than my Camry wagon.
Evidently the cable has been pulled lower now and I might not make it up their drive anymore unless dad pulls the cable tighter.
