I have nothing to add to the above suggestions, but having another set of wheels definitely makes it worth investing in a decent pair of road type tires. It is so simple and quick to change whenever the need arises.I do pretty much the same thing, just in reverse, on my 700 C commuter/errands bike. I have mounted up to 37 mm's on it and think 42s would work. I have shallow knobbies for gravel/light trail, a deeper tread tire for snow/ slush, and nice road 28s for pavement.