jamesinc;6306 wroteThe easiest/least destructive option as I see it is to mount them to an L-bracket that mounts to the bumper through the number plate holes.
... Or the bolt holes underneath the bumper. Either:
1. Stand two brackets off a little from the plastic bumper cover. i.e. A few washers the same size so tightening down doesn't ruin the bumper cover, then a nut (or skip and go directly to...), a bracket, then a split/locking washer and a nut - all on a longer bolt if necessary. (Using stainless steel hardware from a boat place maybe.)
2. Same as above but a single horizontal bracket spanning the two holes - then mount the lights the distance apart you prefer.
And... Considered an "LED light bar" mounted under the bumper? (Don't know if that's the correct name.) I see them in auto catalogues all the time, but have never actually seen one turned on to judge their light ability/spread. Or how it would look (aesthetics).