I suppose you could. The 1500 grit sandpaper was still a little hazy but even that was better than what it started out as.
I guess I would see it as a point of diminishing returns. You could go to 2000, 2500 and possibly 3000, but you are adding in a great deal of time and still removing plastic material from the lens, albeit small amounts, but nonetheless material.
I like the idea of polishing the capsule because you dont have to worry about any runs, masking off stuff and so on. However, that too adds additional work. Whereas with the clear coat method, once you get done with the sanding, you clear coat, dry and your done (provided there's no runs or cracks). Furthermore, you have as I mentioned above, the barrier. With that barrier, any future damage can relatively easily be 'buffed' out for the lack of a better term.
Essentially just hit it lightly with some very fine sandpaper (1000 grit or so) and then polish it. There is pros and cons to each method. Personally I liked having that clear coat barrier. Id rather have dead bugs, dust and sand pitting and eating into that rather than the plastic lens personally. Additionally I was also thinking in terms of offering this as a service locally. In that thought it seemed better to me to have the clear coat on there so that would offer some long term protection for the customer. If they decided down the road to buy one of those headlight kits from the parts store down the road, it will work better with the clear coat than the plastic.
I have yet to see one of those kits work with any moderate to heavy damage to headlights. The ONLY time I have seen them effective is in extremely minor scratches or oxidation. If its pitted, forget it.
Anyway, thats my perspective on it. I hope to have a lot more data this coming spring as a friend of mine has talked about working with me on this and I hope to be able to do several sets of headlights and work on the process some more.