Yeah, I don't like to alter the basic functions of a firearm, especially an expensive one. I like to keep things as OEM as possible. I've actually ordered the mag tube and paddle release from Rxarms because we're both in Canada. It's a simple piece, seems fine enough. I'd suggest a light, especially considering it's use in the house. I got an AVA mount with a SF 600 light on there from StrangerDanger and it sits perfectly in front of my left hand. I've heard good things about the IWC light mount too.
I had a mag extension and it wasn't ideal. Makes disassembly annoying having to get the spring in and out every time. Would highly recommend a 1-piece mag tube. Luckily you have lots of options in the states, with the catch of 922r lol.
I guess this gives me an excuse to post it lol. I'm hoping to switch to an entry, then it needs a velcro saddle, CompM5, and some paint and I'll never let er go.