Our local WB dealer will indeed make house calls... within reason, and in our case we're within about 10 miles. Still, we have our own trailer.
You might be able to borrow one, or get a bud to help tow one, etc.?
We have a small leak, too, not easy to find but I haven't spent much time with it.
Hint from dealer: It's much faster to fix if the user can find the leak in advance. That way dealer's time is usually a simple and quick fix. If they have to spend time finding the leak... you're at the mercy of their work schedule.
Hint from our dealer: it's easier to find a leak when the tubes are not fully inflated. When the tubes are full inflated, the higher pressure tends to seal the leak a bit so soap bubbles (or whatever) aren't as easy to find.
Hint from dealer: if it's a valve (check those first), those are usually user replaceable... although I think he meant he'd lend me their tool to do it, save me hauling it up to their shop.
South River, Chesapeake Bay