Try to get it balanced without the canopy on first, then worry about keeping everything in the right spot when the canopy is put on again.

My 1800mah battery is SIGNIFICANTLY bigger than the stock 1000mah battery, so I was surprised that it could fit OK under the canopy. Is the canopy really forcing the battery back in, or could the battery stay there if it was held better? If that is the case, stick a metal nail file under the battery to support it (you can attach it with a small zip-tie), and then stick a block of styrofoam behind it in the battery tray - so it can't easily be forced back by the canopy.

Got to be soime way to make it balance!