Whow, but you find changing a chain every 3000 km too troublesome? If you do so much hassle to avoid it? Sorry, but there really is some irony in that...
(No pun intended)

What I do on tour is I take some wd40 in a little bottle and Clean the chain with a cloth soaked in that stuff when necessary (I hear when my chain needs some tlc - it gets too loud). Then I apply some lube. But that is not different from what I do at home. When the chain gets too long I change it. Usually every 3-4000 km.

Works for me. My next touring bike will have a belt.