Do
((22 / blender units) + 245) / 256, then project from view (bounds) while you are facing the face you want to apply the SIDE texture to and stretch the UV amount in that direction. (s, and lock with x or y)
Like, if you have a 2x wide thing that'd be 2 bu, which in the formula it translates to 1, because 2x studs wide is actually a perfect map in-game.
You can see the blender units by pressing N and enabling Edge Info: Length as such
End results:
The big one was stretched by 1.0107 and 1.0351 while the smol one was stretched by 1.0429 and 1.1718.
The closer the width is to 2 the closer to 1 the stretch is. Values more than 2 should return a stretch less than 1 while values smoller than 2 should return a stretch bigger than 1.
I held this in for a long time now as I keep saying I'll remake the brick tutorial but I am too lazy for that so just take this.
I might or might not just make a video about this if I am not a lazy forget like I am.
This also might or might not be optimal for DTS stuff. I made the formula up long ago for General's BLB converter. For DTS taking account of real sizes you might have to double your BU.. I don't recall how that part worked.