I dunno how I missed this thread before. OH wait, yes I do. I've been reading that fricken cohabbing thread too much.
Anyway, here's my situation. I live alone, but my girlfriend is over a lot so that helps with the burm stuff. I don't think there's a magic number when it comes to length where a snake is no longer safe to handle alone. I think it's a rather vague idea brought about by length/weight and attitude. I don't own a retic, but I take care of one at the zoo and given a 10' retic and a 10' burm, I'd more readily handle the burm myself in most cases. They're both big enough to do some damage, but a lot of times the attitude is totally different.
Anyway my burm's cage is posted here -
http://www.cornsnakes.com/forums/showpost.php?p=491495&postcount=3
The cage is homemade (by the previous owner, not by me... I'm in the process of planning one that isn't so tall and looks nicer
. It's 8x4x4 (again it doesn't need to be that tall), and it has 1/4" plex sides. Realistically, a big snake will have no trouble going though 1/4" plex if it really wants to hit hard, so that's one thing you have to plan for. Anyone wanting to own a big snake needs to understand that it will eventually need its own room. You can't exactly put a cage or snake that big in the middle of your living room and not have it get in the way.
My burm is around 10'5" and 50 pounds or so, so she's still fairly small for a burmese, but I have no less respect for her power than one twice her size.
And to put it in a little different perspective, you know that vague idea of "how dangerous is the snake" I mentioned above? I think it has something to do with the handler too. Not that any amount of muscle is going to get an 18' burm or retic off of you by yourself, but obviously a 6'6", 300 pound football player might stand a better chance than a 10 year old kid.
I'm a 24 year old zookeeper so I'm supposed to be a professional, but beyond that I'm also 5'8" or 5'9" and 130 lbs, and I never let myself forget that when I go in with a large snake or gator, even with another person.