You certainly are 'getting away with it' Mike on the headlight wiring - I suppose the warm glow from the dipswitch and wiring will make up for the poor Minor heater output.....
Actually the original dipswitch and "pull" type light switch seem to take the extra current without bother; over the years there's been no warmth, flicker or distress. The size of contacts in them (so I'm told by those who know) are much greater than they need to be for their original requirement. The later "flick up and down" switches I know nothing about. But the use of relays and extra fuses is, of course, the way to go.
Re rear fog lights, I definitely think they're a very good idea for Minors. From behind my rear lights even though I've fitted silvered plastic behind the bulbs to increase the rearward light output (something I think you drew my attention to, Roy), when you follow my Trav at night it still looks as though its fitted with a pair of glowing fagends. And in any fog or thrown up spray they're often invisible!
Regards, MikeN.
Morris Minor, the car of the future. One day they will all look like this!
Yes - the 'silvered' plastic collars make a big difference. Bulbs do lose brilliance with age - so new bulbs can make a difference too. If there is traffic behind - you shouldn't have rear fog warnings on anyway! Blinds the driver behind - and obscures brake lights.