oilman wrote:To the OP
Carrying
There are safe options for carrying in your situation:
Belly band
Kangaroo carry
Various fanny paks
Remora Holsters
etc
There are also options for keeping a guns safely nearby for example a quick assess safe such as a gun vault.
Answering the Door
Do NOT open the door. Many bad things can and have happened when people open the door. Google The Dartmouth Murders
Install a peephole (although a perp can block a peephole with his hand).
DO let them know someone is home there have been situations where people have not answered or verbally responded to a knock and the person then breaks in assuming no one is home.
A chain is worthless (as others have said)
Residential doors are easily kicked in. You can install long throw deadbolt locks on the doors but it is more secure to also install a reinforced strike plate that the deadbolt goes into.
Stay safe.
If someone covered the peephole after ringing my doorbell, the next thing I would do would be to loudly ask who it was while stepping away from the door and unholstering my G21 or leveling a shotgun at the door, depending on what I happened to pick up on my way to the door. Covering the peephole seems like an overtly threatening act to me.
If they didn't answer my question, it would result in a 911 call by me.