It's low to the ground like an air mattress. They do have inflatable bed rails currently in stock: https://www.amazon.com/Shrunks-Inflatable-Toddlers-Children-Comfortable/dp/B00J0YTT72?ref_=ast_sto_dp&th=1
Try these. Put them under the fitted sheet. We use them on our kids on vacation, but they should work just fine for adults as well!