The problem with craters being the exact size and shape as vehicles...
Is that when things blow up, they don't always stay the exact same size as the footprint of the original.
What I've done a few times, when things were only partially glued (Like the two side sections of rhinos being assembled, but not glued to the rest of the rhino), is just pull it apart and leave it in a heap where the vehicle used to be.
Unfortunately, this doesn't lend itself to all types of tanks, or ones that were assembled and then painted.
Anyways, throwing my hat into here, I use craters. Small ones for rhinos and walkers, bigger ones for land raiders, or if there were multiple vehicles that blew up next to each other (Like, say, a rhino exploded and left a small crater, and then a second one exploded near it, leaving a bigger crater in between the two. Specifically, the one that's shown in the moonscape image.)
40K Armies Played: Space Wolves, Space Sharks, Orks, Tau, eventually CSM (MSons + Bile)
Blood Bowl: Ought'Ta WAAAGH Roughriderz (Orcs), The North Spire Wendigoes (Norse) Iron-Wrath Krakens (Chaos Dwarfs, WIP), Scarlet Fliers (Dark Elves, WIP)
Heavy Gear Blitz/Arena: Peace River Defence Force, Paxton Gears in Arena
Necromunda: MacGuffin's Marauders (Van Saar)
Malifaux:Built: C.Hoffman Boxed: Rasputina, Pertitia, some extra models for both
(I'm Mike, by the way. Easier to remember than Tokkan, probably. DEFINITELY easier to pronounce)