The Jacaranda is about 6 feet tall and the other, the Ficus, was damaged two years ago but is growing back nicely and looks like a shrub but the trunk is so short and there is no way to tie something down around it.
Well, what you’re trying to do is keep frost off the foliage, one way or the other. Wind usually does that, if it’s a steady wind. Plantings that are sheltered from that wind, say on the side facing away from the direction of the wind, might still be at risk. That frost has to come from somewhere, and in a typically dry climate such as yours, I’d think widespread, saturated ground would provide the moisture to create it.
Good luck with whatever you decide to do. I’ve lost a beautiful mandevilla to frost before, it’s discouraging, I know.