It's not V7, but V6 in JavaSciript via emulation has been done twice[1,2]. aiju's code in particular would probably be fairly usable as a base if you want to build a version of V7 that runs on from an RK05 disk. V7 does have drivers for it (/usr/sys/dev/rk.c), but none of the default installation tapes have a kernel with support for it. You'd have to install V7 once, rebuild with RK05 support, copy your entire installation and the new kernel to a RK05.
Or you could code a JS driver emulator for the RP04/05/06 to plug into the code.
That's weird because I used an 11-45 with RK05s running V7.
afaicr there was an informal distribution mechanism were you could get a bootable RK05 cartridge from another site so I suppose that's how they got it going.
So I've been digging around and there's another issue. A single RK05 is simply too small at 2.odd megabytes capacity. I assume you did have multiple RK05s in there and split up the filesystem. If so, then aiju's code would probably need other intensive modifications to support multiple of them.
They had a CDC disk pack type drive for the main filesystem (80 meg I think). I guess it is possible they bootstrapped it from a disk pack from another site with the same kind of drive, although that seems a little unlikely. Perhaps the interface was compatible with RL05, something like that. The machine did have multiple RK05s but I don't think they were used beyond boot and transferring data to other machines on campus.
Or you could code a JS driver emulator for the RP04/05/06 to plug into the code.
[1] http://aiju.de/code/pdp11/
[2] https://github.com/takahirox/pdp11-js