The fact that I'd be driving a Triumph TR6 would have no impact on the number of miles I'd be willing to drive. From my home near Knoxville, TN, I've driven my TR6 to Colorado, Key West (several times), Wisconsin, Canada, Maine, Pennsylvania (3 times), Illinois (4 times), Maryland, and numerous trips to the surrounding states. Except for the trips to Canada, Colorado, and Maine, these have all been one-day trips, driving nonstop each way, and they've all been solo trips - no co-driver. The trip home from Wisconsin was 18.5 hours, and I still felt refreshed when I got home. There's something about driving a TR6, top down, warm weather, that's hard to beat.
If properly maintained, and it's not at all hard to properly maintain them, a TR6 can be used just like any other car.