Should work fine, using the ultra light wet paper for very light roughing, a degreaser like the Eastwood PRE or equivalent. Imron clear-coat is a polyurethane, which I am sure you are aware and used the term "laquer" in the generic sense. Should work well unless you burn through into the paint very far, silver may be more difficult than a pigmented coat due to the high level of metallic and light reflectance.
I used 3000 sandpaper on my headlights and they were still very dull afterwards. You should get a very fine polish for the finish. There's a special 3K clear coat that professionals use when spraycoating headlights which also has good UV resistance. You should look for that.
I tried a normal clear coat on some headlights I had in my garage, it looked terrible. So beware that it's not that easy.
regarding the comment about headlights, our 2004 XC90 was starting to get deterioration that was actully physical in regards to the finish of the lens actually starting to "micro-crumble". I used 2000 grit wet sandpaper with a drop of soap suds to take it down to a nice uniform finish, and then a "polish" (which still has an abrasion to it as opposed to a "wax") to finish the job. The results were like new.
You can buy an inexpensive container of "plastic healight restorer" at auto parts outlets, but if you have actual flaking and physical deterioration you will need to remove enough material with the wet sandpaper to get down to a good substrate. This works, and it works very well.