Did some investigating about available bikes in Ulaanbaatar today and found following for sale:
Yamaha 450 Meca Dakar bike in very nice condition
KTM 500 Rally light
KTM 450 Rally light
Honda CRF 450 X
A few XR
This is good news and give us some options if shipping or renting don't work, and if brother pay the bill
I don't mind to have a spare practice bike if so I would recommend the Yamaha.