Well, congrats on the new ride. Looks like you’ve got the info you need already so I won’t go on about what could be done with 2X4s. I got a new ride myself but the roof isn’t nearly long enough to properly support a rack that would safely carry my longer canoes, so I’m working on converting a boat trailer to a canoe trailer. That would work for your Jeep as well,of course - but car topping is far easier. At least its the habit we’re in - the devil we know, etc.
Enjoy that new ride!
I would be fine with 2x4’s and have done my share of rack modifications with wood my friend, HOWEVER; this is Margaret’s vehicle and I don’t think she would be as pleased (LOL)? I shopped for the old style Yakima Low Rider rack attachments as I used them on the Dodge Journey and liked their ease of on/off. They are a few generations removed from the current model, but were a C-note less than the “New” version. I have an extra Yakima bar, so only needed to order one. REI’s Labor Day sale saved me some cash on that. So, I’ll have a “New” Yakima rack system for her vehicle for about the price of a “Knock-off” rack. Will take a pic or two when everything arrives.
Oh, Pat, here’s my last wooden canoe rack, it was on our Toyota RAV4 in the '90’s. Unfortunately, I accidentally did a “Dukes of Hazard” type jump with a canoe on it and broke it! Margaret insisted on a “Real” rack after that (LOL)!