i don't agree with this:
"I'd suggest you get a reliable AR platform in SBR if possible, a good sling, a quality flashlight with mount and a high quality red dot optic. Load it with Hornady 55gr TAP ammunition and use a magazine coupler."
Try shooting your AR in your house you will be deaf for days. Try holding it with one hand and maneuvering around or maneuvering around family members. I would go shotgun everytime!!!
12g was old first choice be now i would consider a light weight 20 pump.
Ummmmmmm... all of your arguments against the AR platform apply to the shotgun. Unwieldy in one hand, and pretty freaking loud in a house. And if you're bringing up single hand manipulation of the weapon, let me know how that pump works out for you. Just sayin'...