Yes you can tube them.
Lots of folks that ride in more remote areas carry a tube just in case of a tear that can not be string plugged. I have never had a tear that big before myself. I have needed 3 or 4 plugs to get the hole plugged up and ride out, but it always worked. Pretty tough to tear a DS tire that bad. If you did, you would have to sew or stitch up before tubing anyway. Some have used zip ties to close up the tear and then tubed.
If I were riding RTW or something WAY out back I would carry a plug kit and a needle with HEAVY thread {nylon or polyester or even dental floss} and maybe some thin tie wire and an 18" tube 130 or so because it could be used on front OR rear and doubtful you would ever need 2 at once, so a mid sized tube would be sufficient.
If you are talking about doing it full time, like oldman there, why? Tubless really works. No pinch flats which is what 80% of what my flats have been. The other 20% are punctures from thorns, nails, or screws which are easily plugged with string plugs and those work great.