There is genetic evidence that some people might be natural tetrachromats, though as far as I know only one case has been confirmed, sort of. If this is true these people would have an additional Q type cone cell, with responsivity in the visible spectrum (so they don't see UV). The mean responsivity of Q cells is in between M and L cells with heavy overlaps, so many of these new color qualia are also inaccessible.

I think it'd be more interesting to expand the frequencies that humans can see rather than just add a new color among the current visible spectrum. Many birds and flowers possess features with colors in the UV which we cannot appreciate right now. Also, squeezing more peaks inside the visible spectrum without expanding it might be difficult if we also want to keep these curves decetly separated.

Hmm, but my understanding is that humans who are natural tetrachromats see more colors in the yellow-red part of the spectrum

There is genetic evidence that some people might be natural tetrachromats, though as far as I know only one case has been confirmed, sort of. If this is true these people would have an additional Q type cone cell, with responsivity in the visible spectrum (so they don't see UV). The mean responsivity of Q cells is in between M and L cells with heavy overlaps, so many of these new color qualia are also inaccessible.

And humans already can see UV light a little, but the thing that stops this from being visible is actually the lens, which blocks UV light normally to protect our eyes

UV-A is not stopped by the lens and can reach the retina.

I really can't steelman DR, it took me a while just to understand it. Optical illusions aren't very problematic to DRs since they can simply blame our own misunderstanding of the world, a pencil half submerged in water appears bent due to diffraction but since this is natural then there's no problem, it is your own misunderstanding of optics that leads you to the mistaken opinion of the pencil being crooked. 

To be honest I haven't seen any statistics or anything like that, I state that based on my personal experience. I used to be active on a neurology server and basically everyone was some form of DRs (most were doctors and higher education).

DR is also considered a pretty orthodox view among philosophers.

I am not an expert, however I'd like to make a suggestion regarding the strategy. The issue I see with this approach is that policymakers have a very bad track record of listening to actual technical people (see environmental regulations).

Generally speaking they will only listen when this is convenient to them (some immediate material benefit is on the table), or if there is very large popular support, in which case they will take action in the way that allows them to put the least effort they can get away with.

There is, however, one case where technical people can get their way (at times): Military analysts

Strategic analysts to be more precise; apparently the very real threat of nuclear war is enough to actually get some things done. Nuclear weapons share some qualities with AI systems envisioned by MIRI: 

• They can "end the world"
• They have been successfully contained (only a small number of actors have access to them)
• World-wide, Industry-wide control on their development
• At one point, there were serious discussion of halting development altogether
• "Control" has persisted over long time periods
• No rogue user (as of now)

I think military analysts could be a good target to try to reach out to, they are more likely to listen and understand technical arguments than policymakers for sure, and they already have experience in navigating the political world. In an ideal scenario AI could be treated like another class of WMDs like nuclear, chemical and bioweapons.