Does the standard regulator/rectifier need any special treatment or can it just be bolted direct to the 1mm aluminium sheet on the bulkhead.

I've not noticed any threads with problem R1's but loads on blades

ive just bolted mine down to the glassfibre battery tray, works dandy

Just bolt it to a decent heat sink panel and put some heat transfer grease between them. It also best to be in some air-flow.
Mines bolted to the drivers footwell (steel) plate. It's inside the flat floor panel but has a NACA duct feeding air to it.

adrian

could mine be in a bad position do you think?

Could be. Heat is what screws them up hence the big fins on it. It wants to be in airflow and best also to be bolted to something that'll transfer heat.