Try cut a giant patch from old tube.
To expand on this suggestion, it is possible to make your own patches.
A dead tube with a hole that needs a patch larger than anything you have available
A second dead tube as a material donor
And all the usual parts for patching a tube, including vulcanising fluid (ie glue)
Here's the ...
Narrow tyres require higher pressure as they have smaller contact area. Would guess you have something bad around - nipples, sharp edge, etc. I am running Schwalbe & Conti 23x622 for a few months now and have no problems to start @8.5 bars (limit on petrol stations) except they drop to 5-6 in few days - normal behaviour.