Another possible option (easy, although imperfect) -- I manage all of my (numerous) domains, including Querki, through PairNIC, and have done for many years: they're reliable, not too expensive, and professional. The combination of their Forwarding and Custom DNS features gets relatively easy forwarding to arbitrary URLs, although it doesn't preserve the original URL in the browser bar.

For example, http://lochleven.net redirects to House Lochleven's Pennsic Inventory / Wiki Space on Querki. Admittedly, I haven't tried doing this with subdomains yet, but my understanding is that it works easily...