Ok tihs is only a suggestion, try to warm up the bike up a bit so that the bolts are warmer, go for a ride then soak bolts by spraying WD40 all over them, so that it penetrates in the grooves, go for a ride again get it nice and hot and then try again to undo them. The reason I am suggesting this is because I have seen a mechanic once, warming up stiff bolts with a blow torch a quite close distance however never near a fuel tank, usually exhausts bolts because they get really gritty by all the crap that a wet road throws on to them and because some idiot uses loctite on bolts!

It might work!