No problem crossing the border. Just a shitload of stamping (especially on Moroccan side). Took us about 4 hours total. Don't bring alcohol, they search your car on Moroccan side(for some weird reason even though you're leaving their country).

Paid nothing on Morroccan side and 55 EUR for the visa on Mauritanian side and I think something for the passavant. Visa office in Mauritania is run by some nice guys, took about 15 min (so way easier than getting it in Rabat!!).
Do not buy insurance for Mauritania on Morrocan side, almost 4 times as expensive!! Just after you finished everything on the Mauritanian side and you're through there's a exchange and insurance office there on the left. Think we paid about 20 EUR for 10 days car insurance.


Place: Border / Checkpoint

Visited: February 4th, 2018

Location: 21.36462, -16.96062