To a question on his climbing movie Pilgrimage Chris Sharma responded saying Hampi is sacred to the Hindus since it is the birthplace of Hanuman, the monkey god. Also Hampi is a place for pilgrimage to the boulderers, since boulders are temples for them.
One good thing about bouldering is that it is by nature the most environmental friendly adventure sports of its genre. It creates very few thresh and damages environment the least. Make full advantage of this virtue of bouldering.
Follow a minimum consumption pattern. Pick and carry back from the bouldering site, what ever thresh is generated during the session (empty water bottles, chocolate wrappers, chalk bags...). Anyway the next rain will clear the few chalk powder marks you have left on the boulder surface, take care of the rest by yourself.
Law does not allow bolting, though you may find some stray attempts made.
Again, you may not be allowed to try the boulders located very close to the monument sites, thanks to the protection concerns. Any way Hampi has no dearth of its boulders.
The dilemma is... the close you go to the protected sites, they may ask you to go away and try, thanks to the preservation concerns. The far you go, they may ask you to go close to the tourist area, thanks to the safety concerns.
Nevertheless it is not very hard for you to find the balance and settle. Happy climbing!