To write the initial one, you need to use -r. This is just the annoying way that disklabel(8) has ~always worked.
I looked through disklabel(8) to see if something else could be done, and I tried lots of other things. I've used "-I -i" for ages, and I see:
-I If a label cannot be read from disk request the default one from
the kernel. Implies -r.
I'll play with it some more.
-append ?root=ld0a?
On my qemu command line and it boots right up without prompting:
Right now I'm using GPT wedges, so I'll give it another try with disklabel. Perhaps a properly disklabeled disk will boot automatically.
Thanks! John