we use this rack -
Slikfit Fastrak Bike Rack
$45 - and it includes the two quick release mounts
got it on eBay
will need an adapter for thru axle mount
That is indeed slick. I don't think you could buy two fork mounts and a piece of 2X6 for that.
As for thru-axle adapters. As you probably know, they are available. The problem is that the ones I've seen that adapt a QR mount stick up substantially above the QR mounts that they adapt to. So your handlebars might be too high for the SUV. You might see if you could actually replace them with regular TA fork mounts. I got mine (see my photo above) from an EBay seller. They're 3D printed from carbon fiber. Low profile so the handlebars aren't any higher than when I used a QR mount.