You have VERY HIGH expectations.
Champagne plans on a beer budget.
You still haven't said what your budget is.
You should get a used small motorcycle, maybe a dirt bike.
Then 50 miles on a motorcycle is not a problem, right?
Budgets not a problem....
It will pay for itself in a couple of uses...
Discounting the price I could sell it for used, it will possibly even break even for itself in a single use.....
I'd like simple, light, and reliable enough to ride down remote roads/gravely dirt forest service roads for a few hours at a time. Some hills. find a decent used bike for about 200 bucks..... And $800 all up isn't that big of a deal. Including new smooth tires... And a big azz cushy seat.
Motorcycles are much heavier, harder to get in and out truck bed, require license and registration, etc. Harder to walk into the woods and hide.
I've already got two places in mind in Arkansas I know I could use it and save either $150 that would be paid to shuttle providers....or a couple days of my vacation time that would be required to hike some trail out-and-back as an alternative. My vacation time has some value to me too.... I hate wasting a day hiking something I already hiked in the opposite direction.... I don't do that to save money, a lot of people do.
Plus getting a new toy that could be used near home seems just kind of fun too. Might be good to take camping as well at places like state parks and such.... Get around without having to drive your vehicle.
Friction drive still seems good to me.
With the honda gx50, the roller would be bigger, and I'm assuming probably slip the minimal amount when wet, or at least less as compared to a smaller engine and a smaller diameter roller.
Lots of the friction drive reviews were 10 years ago.. at that time Staton and seem to have a knurled roller and today it's a grooved.... Obviously that must be an improvement compared to back then to make that change... Or else it was cheaper and easier to manufacture.
The thing about wet weather is edges are what grip. That's why your tires have siping on your car. That's why boat shoes have soles that are smooth with lots of little slits across the bottom of them.... that's how you grip a wet boat deck. Those little razor thin cuts in the tire tread are what grips the road when the road is wet . The more edges the better the wet grip will be. The thinner the ribs on the drive roller and the more of them there are in contact... the better the wet grip would be too.
Along those lines people have been known to take razor blades and slit tire treads and things to create better traction when wet..... Anybody ever tried that on a friction drive bike?