We are experimenting with an intercom system and earplugs
Yes, that sounds like a good solution to try. The Cardo Sprit is similar in concept to the Packtalk that I have been using although the Spirit uses Bluetooth which has a shorter range (only relevant if you want to communicate using your headset with another vehicle behind).
Being able to converse at speeds is transformational - although we always remove the headsets as soon as we get on nice country lanes so we can have the full birdsong-and-engine-roar Morgan experience.
If using earbuds rather than ear defenders you could also investigate custom-moulded earbuds which make an enormous difference to sound insulation.
One of the tips from the Caterham community was that headsets are very helpful when taking newbie guests for their first ride — I can check on how they are feeling before we ramp up the speed and cornering …. I have found this very helpful.
My wife likes to wear a hat which is incompatible with headphones.
Actually I have the opposite situation: headphones are a partial solution to headgear being blown off :-)
