I've repaired literally hundreds of wheels as follows:

After determining that a wheel can't be trued via tensioning, i.e. after it is certain that a straight rim can't coexist with uniform same-side spoke tensions, I'll put a mark on the rim sidewall corresponding to the location that the rim is bent worst, then lay a 2X4 on the ground with the rim's high-spot against the board, then push down to either side of the high spot.

This is followed by a round of evening out the spoke's tensions, and the entire process repeated untill the rim is true and spoke tensions even.
Note if the bend is near to the rim's non-welded seam, the seam may become mis-aligned, and that can be fixed lastly by light swatting with the 2X4 BEFORE any "sanding".
I always use audible plucks to most quickly establish relative tensions, but note that the adjacent, crossed spoke must be damped with a finger while the inspected spoke is plucked, or they'll ring together.

This can be very time consuming in some cases, but a very strong, evenly tensioned wheel can result. Practice improves speed and quality of the finished work.

Best of all, if the wheel is perfectly tensioned pre-trauma, the board-heave method restores spoke tensions as it straightens the wheel. I've had to fix a wheel (against a trashed coffee can in this instance) while racing off road, and the previously well-tuned wheel came back immediately to an almost perfect and reliable condition.

Best of luck,

Dave