Cold-ish tolerant succulent trees

[nsp88]

Are there any succulent/caudiciforms/"fat" trees that can handle down to the 30s? Greg mentioned burseras in his post about his new book, and I had never heard of the genus so I looked them up. I am reading they can survive down around freezing, so that is a new one I hope to get into some day.

Are there any more that can handle down near that low?
Would like something that could stay outside most of the year here. Not required, but bonus points if it makes a good "bonsai."

I like the blooms and the potential for chopping, grafting, and bonsai with adenium, but it is finicky with temps so I don't want to get too many of those (we dipped into the 50s for a couple of nights and it lost most of its leaves).

Plumerias are beautiful and can stay out surprisingly cold, which is nice.

I think I recall hearing that some beaucarnea can handle around freezing when dry.

Any other options?
Thanks!

Edit to add: excluding yucca "trees" here