DIY 14 gauge Uni-Strut as head rail

https://www.grainger.com/product/45YW46
$17.93

This doesn't extend all the way but this covers the length without wheel well.
This one also need drilling on the strut for 3 holes.
You can also get the slotted ones which does not need drilling.​

Screws:
https://www.homedepot.com/p/Everbil...tainless-Steel-Machine-Screw-801138/204274569
$1.13 x 3 = $4

washers:
https://www.homedepot.com/p/M6-Zinc-Plated-Flat-Washers-4-Piece-803548/204276430
$0.68 x 4 = $4

The channel is taller than the OEM rail so it doesn't sits on top of the wall, you need 5 pieces of these washers per screw, on the backside not front, so that the channel can be level. (See pictures)
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Total: $26
(Not much cheaper than OEM rail.)

Easy install from there:

 

Is this for the same purpose as the factory side rails for mounting the tie down brackets?

 

Yeah same purpose.

I have some strut attachment so I figured why not.
Also the attachments are cheaper.