Lower tire pressure on wider rims?
Running 23 mm tires on a rim width of 23 mm is insane -- your tires should be around to 40-50 mm. 

To summarize Sheldon Brown's page:

Narrow tire on wide rim = pinch flats + damage from road hazards (which is the case you are in)

Wide tire on narrow rim = sidewall damage + rim failure and bad handling

You need to get a narrower rim for the bike (or possibly do a 650b conversion if possible, so you can run decent sized tires).