WSPR is a very viable option for 22 meters, Alex. as a search of the LWCA.org message board would reveal. It is roughly equivalent in detection efficiency to QRSS3, which is the "gold standard" for the band, but has greater data throughput per minute.
There are currently two stations active in that mode, K3SIW and K5LVB, another that uses WSPR intermittently (WA1EDJ), and a Canadian who uses the call J1LPB has been on in the past but hasn't been reported in quite some time. All the currently and recently active WSPR stations employ an Ultimate 3s as the transmitter, with the output stage modified and/or an RF attenuator at the output to get down to the necessary power level. There's a WSPR test generator kit being sold (I forget the name of it) that has been discussed in some forums which apparently has a suitable output. It's popular for 30 meter ham beacons, although I'm not aware of anyone actually using it on 22 m.
But the very first WSPR on the HiFER band was seven years ago from Jim Vander Maaten (former beacon ESA), who was generating it with a Raspberry Pi that he also used on 30 and 20 meters, if I recall. He only ran it on 22 for something like a day and a half, unfortunately. During that time I could see it on an Argo screen, but I wasn't familiar enough with the WSPR decoder software back then to set it up for nonstandard off-ham-band frequencies. By the time I got the hang of it, he had abandoned 22 meters, so I had to wait a few more years until K3SIW put his WSPR beacon on the air. The article about the R-Pi that Jim mentioned back then is still on the Web:
http://soldersmoke.blogspot.com/2013/03/wow-raspberry-pi-as-rf-transmitter.htmlAs for other "new fangled" digital modes suitable for QSOs, Dave, it would sure be great to experiment! PSK-31 has been tried, but its bandwidth was too large to be effective in this band, except locally. Slower versions of JT mode would probably be at least as effective as WSPR. But one significant problem is that no one currently offers a suitable exciter for real-time keyboard to keyboard communication on this band. So far, all the available and/or adaptable kits have been intended for beaconing, meaning they have to be reprogrammed each time the outgoing message changes.