M4 as home defense I dont reccomend especially in a vinyl village unless 9mm. Literally the 223 round could probably penetrate 10 of those double wides. Listen to the experts and go with a 12 gauge. I love my Saiga 12 with the 12 round mag full of slugs. with the bolt hold open just feature u dont have to keep one in the donkey. If you need more rounds then that your in trouble. Cant you get 30 round mags for the Glock 19?
Might sound silly but what are those magnetic holsters they make that can be screwed and mounted anywhere? You could get pretty creative with locations using those.