It took us a few tries, but we now have a great system for our kayaks on my 2011 GT.
Starting out with a set of Yakima Timberline Towers on the stock roof bars.
Attached some nice wide JetStream bars with two sets of SweetRolls (do you think I like Yakima or something?) that allow the two kayaks to sit flat, as opposed to turning into giant sails like they do with J-Hooks.
I always recommend using front and rear straps in addition to the two rack straps. I found some hood loops that anchor to the body under the hood, and then I have this insane step on the back that I attach the rear straps to. It also works as a step to let me double check that everything is solid.
With the boats in j-hooks, it was a lot more likely to catch a gust of air and really feel it pull on the vehicle. They are much better flat, and I have driven for hours on the interstate with no problems.
It does reduce gas mileage a bit, but that is to be expected.
Don't get a tow hitch - get a Beaver Step:
https://www.amazon.com/Smittybilt-27046B-Beaver-2-Inch-Hitch/dp/B004K23KQ0
Solid steel, nothing will damage it. Somebody wants to bump into this, well - that's their problem. Just need a good welded bumper up from made from 1/4" steel, and their car won't matter any longer.
I have a hitch-mounted step on my Tundra that I use more than the bumper (because the bumper is too high for me):https://www.amazon.com/gp/product/B004K23KQ0
This is what I'll use on my R1T or R1S when I get one. :)
Not exactly what you asked for but I keep one of these on an FJ cruiser to make it easier to access the rack from the back.
https://www.amazon.com/Smittybilt-27046B-Beaver-2-Inch-Hitch/dp/B004K23KQ0
I like the beaver step better. Makes grabbing stuff off the roof rack easier: Smittybilt 27046B Beaver Step for 2-Inch Hitch https://www.amazon.com/dp/B004K23KQ0/ref=cm_sw_r_cp_api_glt_i_VWVAR6ZXQ2Y2382XM6AV
i have a beaver step that goes into the hitch receiver and love it
https://www.amazon.com/dp/B004K23KQ0/ref=cm_sw_r_cp_apa_i_2K3gFbR3ZVXEM
If you have a truck I recommend one of these "F your front end" bumpers:
https://www.amazon.com/gp/product/B004K23KQ0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1