*Is* there such a thing as a small gas leak?
There may be a remove the tank treatment that might work, but after restoring a bike which had been treated with an internal leak stop, I must say it can mess up the filter and the petcock and the carbs something bad.
I think a lot of people get the bracket leak - do a search for it here. I think the main issue was having the fix pop open again when the tank was remounted.
One product that works well for gas leaks in general is marine epoxy putty. JB Weld makes some as do other companies. It's like silly putty - you knead it together to mix the chemicals and put it on the thing to be expoxied. It cures in minutes. At the very least it's a good temporary fix. I used some on the "seam" of my tank, where the top piece meets the bottom, just down under the petcock.
MF Battery, Iridium Plugs, RR relocated, Voltmeter, 170/80/15 Kenda Kruz rear tire, DIY Samsonite hard bags, DIY shaved seat with Beaded seat pad ('cause that's how I roll) and the dreaded STATOR CHANGE.
Shining Black Bess '86 VN750, retired for parts after a fried stator and being knocked (kee-runch) in her parking spot.