As the OP stated there's the "right way to organise" and then there's this way.
I entered "Etape Loch Ness" after confirming that it was OK to be riding a recumbent trike, when they released the "Ride Rules" via email, after the cut-off date for refund or exchange/transfer of rider.
Their policy is now
NO recumbent bicycles/fixed gear...etc.
No mention of Trikes.
Even down to the type of handlebars you're allowed NO "unconventional" handlebars (whatever that means?)
Basically UCI compliant!
Even though it's NOT a race you MUST maintain a minimum speed of 13mph!!!
I'd like to see anyone apart from a Tour de France professional rider maintain that speed up that hill (start at around 50m to 393m in 4.8miles)
If you're unable to do this you WILL be stopped and removed from the event!!!
I have suggested to Macmillan cancer that they switch support to "Pedal for Scotland" instead as they WELCOME recumbents and only ADVISE the wearing of helmets.