My family has a summer cottage in East Wakefield NH, about 30 miles south of Mt. Washington. And its true, I've never seen tropo from the north. Several mornings and late nights a week in the summer, and sometimes during other seasons, you can get Boston FM and TV stations from 100 miles away. On occasion even FM from Cape Cod and TV from Providence.
But I've never gotten tropo from the other direction. You're right that if you're in the right place, you can hear 105.1 WTOS Skowhegan ME (57,000 watts from 2450 feet above average terrain) and in other places 92.9 WEZF and 107.9 WVPS from Burlington (with similar powerful transmitters and heights). And you're also right that when you're climbing up Mt. Washington's toll road, it's easy to get CITE-1 from Sherbrooke Quebec, also with a crazy high power and height, with a French Adult Contemporary format.
I remember several decades ago, being about 40 miles northwest of Mt. Washington, in Newport VT. The E-Skip was incredible. I was watching TV stations from Kansas City, St. Louis, Waterloo and Memphis. They'd come in for about 10 minutes, then fade and something else would come in. Of course, this was during analog TV days. It was the best TV DXing I'd ever seen.