Just to provide a slight offset. I've never driven a TR3 so I'm not able to do a direct compare. However, a seven particularly a crossflow live axle 4 speed caterham is more suited to the occasional blat. I suspect the higher HP with a Dedion axle and longer gearing would make a big difference
With the short gearing for highway use, the vibration, noise and wind buffeting, I find I am pretty mentally and physically fried after 3 hours in the car. In many ways that is a good thing as I wanted a visceral and pure experience, but it does dissuade me from going on a 4-6 hour tour and I think my lovely wife would not put up with it.
I know many others have toured great distances in a Seven.