The battery maintainer should provide enough power to maintain the battery without bypassing the #19 fuse. The RVi3 only draws some current when applying the brakes, otherwise it draws almost nothing.
If you continue to have battery problems change the battery. CRV's have a garden tractor size battery and can't support much electrical load. Change the battery to a group 24 or 24F, depending on how the battery cables are arranged, with at least 750+ CCA capacity. You will need to replace the battery tray with one from a Odyssey, about $40 from your friendly Honda Dealer.
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