Plugs tend to be ineffective with tubes...
I wouldn't want to put much faith in a canned fixit solution for a tube either.
To the OP, if you don't want to carry tubes & tires, carrying air could be of limited use. Of our several flats with tubed tires, all but two have been punctures from foreign objects (from screws to screwdrivers
). One was a tube that just gave up (slow leak in the front on a KLR on the track - HIGH mileage on the tire), and one was an oversized tube fitted in a rear KLR tire (don't trust the guy selling you the tube to sell you the right size for your tire...).
The only tubed flat that could (and did) benefit from additions of air without any other measures (for a while...) was the oversized tube, thought it did NOT make it home before the chafing caused too big of a hole to hold air. (We had a spare tube & tools, but did not care to use them at that time in the particular circumstances.)
