Your statements here don't make sense; first you're saying 400 ore in one shot isn't enough and second you're saying you can't compete with obsessive carpet-weavers. If I only use 400 ore with carpet and you use 800 ore without carpet in the same time period, then it is you who are the larger drain on the resource availability.
And WD's idea would help a lot too - add mining rocks in the wild, in caves. Also fix Super Sledge to work as a mining hammer. Oh and the dynamite thing. Guess i should stop right there.
No, you have a good idea here; make dynamite blasting confer a 15% chance of spawning a free private mine if done at a certain mountain map type.