bro
i would not advise you to rent and drive in nepal. if you happen to strike someone by your vehicle, they will torch the veehicle and might even beat you up. remember nepal has changed and the mob mentality rules these days.

if you need to go on a trip, reserve car with driver through some relatives or look for the classified section of a print newspaper.

i do not know the rates for rental.  only saw the rental agency when passing through the road last time i was in nepal.

US license works but you need to get a international drriving permit from the US. you need to have the international driving permit as well as your original US license with you when you drive in Nepal.

dont take the hassle bro, rent with a driver and save yourself some headache. traffic in ktm is sick!