Lynne,
As a permanent addition to your carry-along RV equipment so that you're always ready for anything at anytime, you might want to check out a set of traction mats like the serious off-roaders use.
There's several different styles and prices on these. I'd look for expensive ones like the 4X4 folks recommend - which probably means they would be super strong and most suitable for the weight of an RV in sand:
https://www.google.com/search?q=%22traction+mats%22&lr=&hl=en&as_qdr=all&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwiNxLKbyMzdAhWR-VQKHVsBCRgQ7Al6BAgFEA0&biw=1536&bih=738