I don't know what could be causing that communications error. There's an option in the debugger that you can enable for slow debug machines, but I didn't have it enabled and I was running the debugger fine on a Classic II. I guess you could try it anyway.

Otherwise I think that's much the same as what I did. Of course, it was easier with D11E4 as it didn't need the debugger to run, whereas D7E1 does.