Cut away!
I actually had Regal cut down a brick of the 3B stick to 16" years ago, and they feel really nice at 16". Nicer than the 16 3/4 they are, and way better than the almost 18" the AVH stick is.
I bought them a couple times, and was even on their Christmas card list for a few years, which was kinda cool
Unfortunately, Regal doesn't do any custom sized/length sticks anymore. I tried to get more 4 or 5 years ago, and they just said they don't offer that anymore.
Anyway, I've cut down quite a few sticks to get the exact length I wanted.
My sticks are now 14 7/8 (started at 16") and vary between .560-574 (double butt) depending on what band I use them for.
When I cut mine down, I marked the spot to cut, put it in a vice, used a level to make sure the stick was straight, then I cut.
I used a belt sander to do a slight rounding of the end, which is kind of like a Vater stick.
After that, I had the sticks made to those specs by the company I endorsed (CDX customdrumstix.com--which is very close to taking orders again as their new shop is almost ready).
CDX would be able to make the 16" 3B/AVH stick if you cut and decide you like it (when the shop officially reopens).
Otherwise, you can contact Nani or Jeff over at customdrumsticks.com (basically the same name), and they'd be able to produce that stick at 16" also. They probably already have that stick shape & tip, and it wouldn't be a custom shape order. Even then, as a custom shape, they're only $6.95 a pair with a nice wax finish, and if you like the raw stick, they may even be less than that.
They have real nice quality over there.
Good luck!