Defensive Tools

Compact defensive rifles

Stick with the AR or possibly a 9mm carbine such as a Keltec even though it's not high end or supremely reliable it has the benefit of light weight, concealable folding, and almost cheap enough to not worry about damaging it.  It still slings lead.  Another option is to just go for a .22 in an ultra light configuration that you can wear while working. 

In the end it may just pay to improve your handgun skills to the level that within 50 yards you can still do the job of protecting yourself and others in your home.   With that level of skill you can then reduced your carry weight down to less than 2 lbs except for maybe some extra loaded mags.  The choice then is yours.