o.k., i did some poking around about this issue.
you shouldn't need to run tape with the fs-4, it'll record directly to the hdd without any tape in the camera... with my xl1s, there is a red flashing icon for no tape, but there is also an icon in the viewfinder that tells me when the fs-4 goes into record mode... all i have to do is hit the record button on the camera, because it controls the fs-4 via the firewire.
focus enhancements makes the fs-4 series of hdd recorders, and there is a specific fs-4 pro(hdv-capable) version that has a canon moniker, it's called fs-c.
you can buy the old fs-4(dv-capable) units and upgrade 'em to an fs-4 pro, which a number of people have reported works with the hv20... i think that the upgrade is maybe around $325(??)... way overpriced for what is probably a simple flash on an eprom.
here is a thread about various fs-4/fs-c/hv20 stuff: http://www.dvinfo.net/conf/focus-enh...-topics-9.html
one thing to note is that focus enhancements has declared bankruptcy, but all operations are reported to be continuing as normal.
there are hdmi recording units, but they are not cheap... probably better quality picture than the hdv fs-4/fs-c units, tho.