I recently replaced the lenses on both headlights (I had to replace one because there was a hole right through it due to a massive ball of hail - long story) the other was opaque/yellow because I had previously 'refinished' it but did not keep up with the waxing/UV protection. I also needed to replace the ballast due to water damage. I found it quite challenging to remove the headlights from the vehicle on the passenger side. I removed only the front half of the wheel well, I recall two vertical bolts/screws and 4 horizontal bolts holding the lights in place. I had to remove/shift a number of other cables and mounts and the ballast in order to get it out of the vehicle. I did not remove the oil cooler but I also only replaced 3 of 4 bolts on the driver's side. IMO this job is definitely not worthwhile if you are only refinishing the lights. The ballast can be replaced after removing the 6 bolts but you don't need to remove the full headlight unit from the vehicle as the 4 torx screws holding the ballast can be removed by shifting the headlight slightly backward.

For the lens replacement (eBay $300). After removing the two small screws I convection baked the lights at 270F for 10 mins and then pried the lens off starting at one end using a heat gun to assist. After scraping out the old adhesive, I used construction adhesive to reseal the unit. There were a number of broken plastic bits/tabs but none that are visible or caused any problems for reinstalling. The lights look great now, but it's not a job for the faint of heart.