T2.1, BRT Ocean hexes are Submerged-reef (G13.431)
G13.431, Each submerged-reef hex is considered a shallow-Ocean hex.
G13.4, a shallow-Ocean hex is not considered a Water Obstacle to Inf, Cav, horsies, vehicles (except boats & LC), rubble, & A-T mines. (so a rubbled BRT pier becomes rubble, it don't disappear.)
G13.42, a unit that enters/occupies a shallow-Ocean hex is said to be Wading, a Wading unit is treated as being in a shallow stream.
B20.46, Wrecks do not appear in a flooded stream.
Therefore I assume that Wrecks can appear in a non-fllooded stream, & that they'll also appear in a BRT Ocean hex.
The above is a typical BRT rules-chase.
'sides which, all the burning LVT Wrecks are the only cover the USMC player's entering units will have, after the initial bombardment smoke disappears.