Thanks, demerphq. I've been using sv_dump, which is handy, though it is frustrating that it only shows one level. For instance, it would only show the reference, and not the object (caveat: I'm not sure I haven't got those mixed up -- see my reply to mugwumpjism):

SV = RV(0x182186c) at 0x1856bf8
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,ROK)
  RV = 0x1801380
  SV = PVMG(0x1822080) at 0x1801380

/* instead of... */

SV = RV(0x182186c) at 0x1856bf8
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,ROK)
  RV = 0x1801380
  SV = PVMG(0x1822080) at 0x1801380
    REFCNT = 2
    FLAGS = (OBJECT,IOK,pIOK)
    IV = 3880080
    NV = 0
    PV = 0
    STASH = 0x180b56c   "Artist"
[download]

To find out how to make multiple levels appear, I peeked inside ext/Devel/Peek/Peek.xs and saw that it was implemented using the private function do_sv_dump. Obviously, do_sv_dump doesn't belong in production code, but this is just debugging and it's even handier than sv_dump if you're motivated enough to memorize its 7-argument interface.