OP said:
Why aren't there horizontal gun safes?
There are. Buy a vertical safe and lay it down on it's side. Presto! A horizontal gun safe!
OP said:
1) Don't want my gun safe in the garage, where it makes it unlikely to get to my guns in a defense situation.
2) I don't have a basement.
3) Vertical safes are too obvious.
4) Medium size vertical safes are too easy to knock over. I also don't like the idea of bolt things through my floor or wall.
5) I want my gun safe(s) in the most likely areas I'll need them...the bedroom is ideal.
6) Some safes are way too difficult to move because of weight, size, hallway, stairs.
I fail to see how a horizontal safe would eliminate any of these problems, and I fail to see how any of these problems are specific to vertical safes (not counting #3, which IMO, is ridiculously illogical anyway).
It sounds to me as if you just plain hate the idea of a safe, in general. Each of your "issues" are going to exist with
any well-built, secure firearm safe, whether it's a vertical rectangle, horizontal rectangle, a cube, sphere, pyramid, parallelogram, or other three-dimensional shape.
Having said all that, the concept of locking up the guns you plan to use for HD just doesn't make sense to me. Never has, probably never will. That would be like buying a Glock 26 for concealed-carry, putting a traditional trigger lock on it, and holstering it like that before going out.
I've attached a couple of pictures of a horizontal safe you can use.
Find it for sale here.