SiiS,
1. Do you ever undergo / carry out a proficiency check in a single pilot helicopter without dual controls fitted?
2. Any idea where it says you should have dual controls fitted whilst carrying out a proficiency check?
Question 1 - not until the thread title becomes reality!
Question 2 - CGIaF

k - not prepared to go there under any circumstances! Don't care what the regs say!
Actually once did an AOC "Proving Flight" with UK CAA Flight Ops Inspector (Actually a good friend) who sat in 300C Pax seat with me without duals. he commented " I haven't flown in a single piston since our Navy days"
I hadn't the heart to tell him that apart from my check ride with Denis K, neither had I!
Trog