Alrighty, here's my account of the Bazargan border from turkey to Iran as of mid sept 2019 :
We arrived from Turkey on a Saturday morning at 6 am at the border (2 guys from Switzerland riding 2 tigers 800).
We had the Iranian visas, the carnets and had contacted the old Hossein before hand and agreed to meet him there (info :
mr_hossein_ir@yahoo.com / 09144138096).
We did the Turkish side on our own, pretty easy... people will show you where to go, nothin special.
Than we got to the Iranian side and Hossein did it all for us, which is good because it's a bloody mess.
The whole thing took us one or two hours, we did not get searched, neither did our bikes.
We did not have to buy insurance for Iran, might seem stupid but I was wondering... No one told us anything about the guide things (then again, we're Swiss) and no one cared about the size of our engines (not talking about our privates).
We did not change any money at the border of course, Hossein did that for us at Bazargan city (what a nice place it is by the way). Had a good rate, fair play.
We even got escorted to a hotel in Tabriz by our new friend, who took us to the Sina hotel (25 USD by room, decent hotel close to the bazar). Oh and Hossein showed us a church on the way to Tabriz, scenery was amazing !
Hossein charged 100euros per person to do so. Would do it again.
Might be interesting for some other guys, Hossein can arrange a carnet for you for Iran only apparently. Didn't ask the price cause didn't need one.
Hossein if you're reading this you crazy artist, don't cut yourself with that knife