Bit late, but I happened to be poking around under the seat of one today so here you go. 3XV fitment battery is relatively weedy at just 1.2ah so I don't know if that would cause any issues on an RGV? You would save a bit of weight though and, it being a gell-cell, you can locate it pretty much wherever you want. I use one on the 3MA for those very reasons.
Cheers.
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