I'd just hit the deer.... ;) No way am I going to try some wild maneuver to avoid an animal (towing or not)... I've hit deer before (not towing) and yes, it damages your vehicle and it's a mess, but it's better than swerving then losing control and rolling your vehicle, or worse, going into oncoming traffic..
But, that's just one scenario.. There are an infinite number of scenarios or possible "bad days" out there.. It's just a matter of luck or karma or whatever that keeps any one of us 'safe' on any given day..
And, I have driven in windy, rainy and not so 'perfect' conditions and you know what I do?? I adjust for it... I'm not bombing down the road going 65 mph like it was a nice sunny day...
No one knows what they are going to do in any given situation.. All you can do is rely on your experience and don't panic and hope it's not going to be your day..
Margaret, I'd say just get some more miles under your belt, gain some experience and soon you'll be giving advice! :) We all had to tow something for the first time and even after towing things for awhile, every new rig needs to be learned... But, once you are familiar with your rig, it becomes easier to predict situations and avoid them all together.
Mitch