Key changes required to get working were to set the following boot arg for both the installer USB and the live system
* efi=no-rs
The installer USB also required the nouveau blacklist args:
1. nouveau.modeset=0
2. rd.driver.blacklist=nouveau
3. video=vesa:off
The final iso to USB method used was the Fedora Media Writer with Qubes R4.0.1 iso onto an HP 32 GB usb. Many USBs and writing methods were used, but I can't say which would have worked if I'd gotten my boot args right initially.
Altering boot args was difficult, since mounting the /dev/sdX2 partition didn't allow direct manipulation of the BOOTX64.cfg file. Upon advisement from #qubes on freenode irc, I copied the file, altered it, and then moved it back in place on the USB partition, which worked well.
Post installation, Qubes configuration after initial boot had to be done with TABs, because the mouse did not appear to work properly. After configuration, I found that the touchpad behavior seemed to depend on using a very specific section (top right corner, it seems). USB mouse was a preferred alternative, but it may be true that the initial configuration could have been done with the touchpad mouse if I'd known about the sensitive areas.
Without efi=no-rs, post install allowed LUKS decryption before going black and freezing.
Thanks to all who helped me figure this out, and hopefully this is sufficient payback for the support I got :),
Adam/ilsonno