Vibrations.....

I don't foresee mounting it more rigidly to be a problem.

Here's a few ideas:

1. Buy a larger battery to fill the hole in the oil tank so it can't move around as much.
2. If a larger battery isn't possible you could use a rigid foam to fill the void in the oil tank to prevent movement.

3. Cover the terminals so if something does contact it will not create a connection. My 2005 Ultra has caps over the terminals.

Thanks....I looked into the next size up, dimension wise for the battery. It will not fit under the seat. I think I may have a piece of rigid foam in the garage, if so I will use it until I get around to making a better restraint system.
When I was at NAPA they did not have a boot that would work. Cables on my bike are side mounted so they are resting on the lip just the under the terminals. The boots I have tried just do not fit well. After a few hundred miles they have normally shaken themselves loose.
When I have some time on one of my trips to town I am going to stop at a couple of shops that rebuild alternators to see if by chance they have a boot that will work.
I am not overly concerned with the battery shorting out again, it was my own stupidity that caused it to happen a couple of weeks ago. Just concerned with all the vibrations that the battery will see if it is rigidly mounted. Wondering which is more harmful to the battery, visibly shaking like it does or being rigidly mounted. Guessing that if I rigidly mount it the battery will be absorbing all of the shakes.....instead of just being along for the ride so to speak....