I always carry a small patch box with two superglues, one tire boot, several rubber patches and some anchovies.
If I get a flat that leaks I'll put an anchovie with glue, to avoid the pressure expelling the anchovie. If it's too big I'll glue and rubber patch outside to carry me home. If it's massive I'll use the tire boot inside.
Of course if you have to get the tire out of the rim it's better to have CO2 cannisters than a pump to remount the thing.
Best long term solution for any leaky fixings is a patch inside as recommended above.
Sounds complicated but I've been riding without carrying spare tubes for a year now, usually takes me a minute on the roadside to fix a flat, in many cases I don't even notice until I feel a soft tire and remove the offending glass at home. Hope this helps