Check with Porter's Camera. They used to have a little tripod adapter that you could mount your camera on. You would take one picture and then slide the camera over 3 inches and take a second one. Print the two images side by side and view them in your stereo opticon.
I had a 10D that I regularly shot at 3200 and I thought it was acceptable. The 60D goes up to 12800. Remember, a grainy picture is better than no picture.
Jim Domke designed his bags to hold 4-8 lenses, up to 300mm F4 and still fit under an airplane seat. When I fly, the camera is in my lap, under the seatbelt. I've used his bags for 35 years.
Personally, I used a Quantum gel pack for many years. I never had much luck with AA rechargeables. These days I use lithium throwaways and they recycle quickly and last a long time. And if you buy them at Sam's, they are 12 for $20.
I have run more than one memory card through the washing machine, with no apparent effect. I've heard of them being dropped in puddles as well, with no problems.
This is why you pay the big bucks for "L" glass. I've always said you drive nails into a board with one, and you see to have proven that. Over the years, I've dropped or banged around many a Canon lens and a Nikon or two as well, ( one place I worked provide me with Nikons) , and the lenses never suffered, one Nikon body jammed the mirror, but it was an N90, not an F3.
You can get a star image by either using a small aperture, F16 or smaller, or a star filter and a very wide aperture, like F4 or bigger.
Remember there are two kinds of movement, subject and camera. IS and VR deal with camera movement, subject movement is dealt with by shutter speed.
If your 500mm lens is a yard long, it is probably not a mirror lens. A mirror lens of that focal lenghth would be 6-8 inches long about 4-5 inches in diameter. It would also have 2-3 inch spot in the center of the front element. How about posting a picture of it?
The thing to remember is that there is two types of movement associated with photography, subject movement and camera movement. IS and VR will deal with camera movement, but not the other. Only shutter speed will do that, I think using on a monopod would be OK, as ther is still some camera movement possible. But what the hey, I don't have IS on any of my Canon lenses.
I forgot to mention Royal-X pan at 1250 and 2475 Recording film at between 1000-4000. Talk about grain, more like rocks.
Kodachrome 25 and Panatomic-X B&W film, 3M 640T slide film. Personally shot Tri-X at 3200 and T-Max at 12800. Eddie Adams, Pulitzer winner, was advertised as shooting T-Max at 50000.
I stand corrected. I was not aware that the T3i was capable of that.
Pro stadiums have really good lighting, so TV can broadcast night games. Long ago, I knew a SI photographer who was complaining about having to shoot 800 ASA(ISO) at 1/500 at F8. I told him it sounded like a day game.
I think you will still need a 580 to fire it off , or maybe some wireless thing.