There is a regular vehicle ferry from Sharjah to Iran, operated by the Iranian shipping company, Valfajre-8 Shipping Company.
Their head office is in Tehran, but they have large offices about 1km from the port in Bandar Abbas (between the town of Bandar Abbas and the port, on the shore side of the road).
There is an agent in Sharjah - Oasis Freight (their Dubai office number is: 04 3525000 - they will be able to advise the number for their Sharjah office). This agent is the only handler for the ship, so there is little room for much negotiation.
Purchase your ticket from the agent in Sharjah, and then go to the Customs office.
It's pointless giving a description of my route through this building - a ball of wool has less twists after it has been incorporated into a knitted jumper. Suffice to say, there are plenty of desks, and you visit every one at least twice. There are even offices in the basement which need to be visited.
I needed to retrieve my customs bond from Dubai's Customs Authorities, for which I needed a stamp confirming export of the vehicle. This stamp was not going to be provided until the truck was on the vessel, which would be about an hour before it departed. As I was going to be on the ship, I had to try to get the stamp on the form in advance, to allow me to take a taxi back into Dubai, reclaim the bond, and return to Sharjah.
My vehicle was locked in a bonded compound within Port Khalid (Sharjah) a day before the sailing, and could not return to the streets of Sharjah without clearing customs. Still, the customs authorities did not want to stamp my forms.
In the end, the boss of one half of the Customs Authority authorised the stamping, which gave me the requisit stamps to reclaim the bond from Port Rashid in Dubai.
Back at Port Rashid, the Accounts Department was closed, but the Refund Department promised to refund the money into my bank account. Two months later, I've still to receive the money. They are currently ignoring my emails, so I'm going to start letters and telephone calls. I'm not hopeful.
There is a small shop within Port Khalid for food and drink.
Although there are stevedores who are supposed to load your vehicle, I loaded mine.
You are not normally allowed to sleep in your vehicle on the overnight journey from Sharjah to Bandar Abbas. You are meant to stay in a room with broken aircraft-style seating, and spend the night watching seasick people throw-up. I slept in the truck!