I have non-padded tights and padded bib tights. I don't feel like straps are necessary for non-padded tights.
Personally 50°F isn't cold enough for me to even wear tights, I'd just use leg or knee warmers for the lower body. Everyone's a bit different in the temp ranges they're comfortable with, but usually it's cold at the beginning of a ride and both your body and ambient temp will heat up later, so warmers are the more flexible option.