I visited Fort Munro on my two wheeler on Eid ul Fitr 2010. It took me 5 Hours from Multan approx 180 Km. I did not stayed there and returned on the same day.
You can reach there 3.30 to 4.00 hours. Road is good safe and secure. But do travel in day light only as very less population in the way. (Public Transport is also available from D.G. Khan)
The roads are secure. The traffic is on the way carrying goods and fruits from Boluchistan to Punjab.
Multan to D.G. Khan some part of road is deteriorated due to flood 2010 but easy to manage.
You should take route
Multan-D.G. Khan 100 Km
D.G. Khan-Sakhi Sarwar - Khar - Fort Munro = 80 Km.
On this route you will cross the Chenab River, Indus River, Muzaffargarh city, Thal Desert and then you enter Suleman Mountain Range and cross the Girdu Pass.
Rakhni (Baluchistan) is near to Fort Munro on way to Lora Lai Quetta. You may visit Rakhni.
You can also reach there by Quetta Lora Lai Rakni. Or you may reach D.G. Khan via Indus Highway from Karachi or Sindh.
Hotels are cheaper starting from 200 or so.
No info about the rest houses.
Sher Dil