My guess is no one has done it since there be no reason to do it. It would like cutting a 1522 handguard in half to put it back together again. Nothing is being accomplished.
Technically, there's absolutely no reason for any "Tactical" upgrades to the 15-22 either. No reason for a B.A.D. lever, no reason to replace the factory stock with a Magpul one, no reason to replace the factory sights with Magpul or Duek Defence or Troy, No reason to outfit it with anything that may give you a "tactical" advantage as most of the "upgrades" do to an AR-15 (not that even a small percentage of AR-15 owners in the US have ever even served in the Military or held, fired, etc. a rifle in self defense or tactically for that matter). I'm sorry guys, but no one is clearing a structure with a 15-22... no one is taking a target from a mile away with a 15-22... no one is going into an insurgent stronghold or doing any kind of reconnaissance with a 15-22. What does all that mean? The modifications we do are all pointless, but we do it because we like it. It's fun and we see if we even CAN do it.
As it stands... the existing trigger guard is simply decoration in the first place (as are most of the "mods" that are done to the 15-22). If you shaved it off completely just because the weapon would function 100% as advertised with no change in performance whatsoever. So someone "modifying" the existing trigger guard to incorporate a name brand piece of plastic is completely within the realm of a hobbyist or enthusiast seeing what they can do with their platform.
Why put a $400 free floating rail system on a $600 weapon? Why even modify the barrel with a new adapter to even allow a new rail? Why put a $200 tactical trigger on a .22lr? Competition? Maybe.
The Magpul B.A.D. lever was not designed for the 15-22, yet A LOT of members modified it to fit and even modified their lower receiver to allow for the lever before someone said "hey lets just bend it!".
If everyone just kept what they had and didn't modify or create new means of adding something to it, 80% of the instructional videos on YouTube wouldn't exist.
I realize that it may seem small at this point since it's just a trigger guard... but I'm sure someone said "Why?" when the first person wanted to outfit their 15-22 with a brand new shiny FAKE SUPPRESSOR! Which again, serves no purpose. I mean sure, we write it off as it aids in recoil reduction... but come on.
I agree, there is absolutely NO REASON to change out the trigger guard... but that wasn't the question. Anyone who has seen the pictures of my 15-22 knows I've done MOST of the "mods" and I am all for seeing if it can be done... just remember, I wasn't saying is SHOULD be done... the question was COULD it be done and the biggest and most important question... has anyone actually DONE it. Everyone's opinions as to why it shouldn't be done are moot as it pertains to the original question.
I do appreciate the feedback and I see everyone's point of view... but an answer to the actual question of has anyone done it and what the outcome was would be much more appreciated.
Thanks again to all!