CAAN website >
http://caanepal.gov.np/drone
That sub 2kg thing seems to be specifically for exemption for permissions from CAAN in section 1. (Tourists) and other applicant there.
You may still need permission from the other 2 authorities ?
It seems max alt is restricted to 200' AGL, about 60m, probably due to the amount of low flying small aircraft / mountain airstrips in remote areas.
Perhaps try a click on the link '
Application for RPA / Drone Operation' and have a read further . . . I couldn't get that to open just now (or the other link there) so I think it's going to be an uphill battle with this site.
The country really isn't tech rich, so suspect the website will be limited in help, maybe try and find an email link to write an inquiry.
Edit, that pdf application just opened ok, might have just been a very slow download !!
Looks free permit and very straight forward.
I wish I was into drones in 2012 when we spent 28 days remote in the far NE of the Nepal Himalaya, it is stunning.
Flying would be fairly simple in the more isolated regions, though you'd probably attract a crowd in the villages, and I wouldn't put it up in Kathmandu.