You might offer two options.
Print alone rolled in a tube.
Print mounted on foamboard (or whatever you decide) and shipped flat.
Charge 2 different prices.
I have thought this through many times about my own stuff.
I've decided many times that selling my prints would bring in extremely little net cash,
due to the costs involved and what any sane person would actually pay for one of my pictures.
When the occasion arises, I give my prints away or swap a few for drugs or sex.
(that's a joke guys 😀 )