Via is a small Euro-style (but not Euro-small) A on the Sprinter bare chassis. It has about as much usable space as a slightly longer C, because the cab space is better integrated into the living space than the van cab of most Cs, and it is narrower by 6-12 inches than most C motorhomes, and most larger A's. That width is important, because it is the width of a motorhome, not the length, that puts the greater constraint on finding places in town where you can park.
When traveling and road-tripping my wife and I used my 30-foot, full-width C as you propose, doing our sight-seeing enroute, unhooking to go out if based in one place for more than a day. However, we planned our travel days to do this, minimizing the ins and outs, and simplified our hookups (power cord only) when we planned to go out.
Hookups are not the real work involved in going out. The real work is putting away everything inside so that the interior is safe to carry people. Several trips with daughters, sons-in-laws, grand-daughters taught us that this becomes a whole lot more work with more people, because you have to shuffle people around to do the job, when they are still focused on getting ready to go out in public. Often much more work with girls, than with boys.
This hassle of moving people around to get the RV ready to go gets a lot worse if you are converting back and forth between sleeping space and living space. Sometimes with youngsters you can get them dressed quickly and send them out to the playground while you work, but this is not my experience with teen girls.
I've never found leveling a problem, but I tend to choose RV parks and campgrounds with level RV pads. Most of the time I get level enough moving around on the parking space, sometimes need and inch or two of blocks at one wheel, sometimes two wheels at one end, e.g. on a perfectly level pad because my MH rides low in front when I've adjusted weight distribution for handling.
I think a 25-foot motorhome, whether A or C, is going to be interesting with a couple of girls getting into their teens and wanting private space more often (I raised two girls and grew up with four sisters, adolescence gets to be an interesting experience). An actual C, with cab-over sleeping, could give them their own "cave" but with two they must be of a disposition to share that space. In the Via, 25T might work if you let the girls have the twin beds, and you are inclined to use the drop down bunk, which can save some of the trouble involved in converting dinettes and sofas while people think they still need to use the space.
But with patience, most anything can be made to work. I recently finished a week long cruise in a cabin occupied by three adults and two 11-year old girls. It helped that there was a closed off bunkroom for the girls, and there was household staff to convert couches back and forth to beds while we were out of the cabin. In the RV, that's something I have to do myself.
FWIW, I do have a vehicle set up to tow, on the second one now, but when I use it is when I am going out to one place for an extended period. I still don't take it on sightseeing trips, because towing a car so limits where the RV can go that I am forced to go from campground to campground with the RV, and use the towed vehicle for all of the sightseeing, rather than having the conveniences of the RV (kitchen, toilet, place to nap) for the day.
Tom Test
Itasca Spirit 29B