Ash,
I don't know if you are in the UK or not -- as not everyone on this forum is. At least I'm not.

I know of one of the best, if not *the* best lens developer and custom 'fitter' (sorry not sure of a more technical term, I'm sure there is) in the world. He is located in the United States, in Texas. I can give you his information if you wish to follow up and are willing to travel.
From all the reports I've read and personally talked to him -- this is highly worth the travel. It isn't cheap, a few thousand dollars if I recall correctly. However, the general treatment is you travel to his location,.. stay a few days or so and go back home. The few days are for him to process your eyes, get them made.. then further 'tweak' to your eye shape and vision correction in the following days.
I can't explain the technical process of what he does exactly, but he works largely with a scleral design (though will work with other forms if you so prefer) -- basically meaning the contact rests essentially on the 'white' part of your eye instead of ON the cornea. This generally allows for much more comfort.
This would be good for you due to you achieving better vision with your contacts already (which is common in KC) but them being uncomfortable and even popping off (which is also common).
He would, likely, be able to custom design some lenses that give you optimum comfort and usually provide the best possible contact 'lens' correction currently possible.
I've questioned why this guy over everyone else -- but from what I can tell just like some great artists or sculptors etc -- he has a passion for what he does, he has developed a 'niche' with this process and he has , apparently, an ability to know how to mold and adjust the lenses to best fit KC eyes. (Which are notoriously hard to fit).
Again though, don't know your location -- and it is some money.
Otherwise, it seems like everything I know of has been mentioned. Basically you have contacts, glasses, (recently - CXL, Corneal Cross Linking), and ultimately a graft if it progresses to that point. Usually glasses only work so much, as with KC we need something that is PHYSICALLY on our cornea to reshape it properly to bend light the way it is meant to be. Glasses typically (for obvious reasons) cannot do this.
As for the police:
I'm sure there are differences in the various states, departments and so on.. but as an example, for the San Diego Police Dept this would apply to you:
If you wear eyeglasses or hard* (non-orthokeratology) contact lenses, your uncorrected vision may be no worse than 20/70 both eyes together. Uncorrected vision worse than 20/20 but not worse than 20/70 must be corrected to 20/20 both eyes together.
* "Hard" contact lenses also include semi-soft, semi-rigid, semi-permeable, gas permeable, and similar lenses.
Good luck,