Thanks for the replies. What I did was put the battery in without the spacer and cut the zip-tie that holds down the positive cable to get some flexibility. I also found that the positive will sit flush on the terminal better if you rotate it a bit to clear the side terminal lump. To get the connector on the positive to clamp tighter, I removed the little washer/spacer that is in the middle of the connector. If you look at the connector this spacer is in the middle of the spilt that the bolt goes through. I don't know why it is even there, but mine seems fine without it. Once I got the terminals clamped down I was still able to use the stock hold-down bracket and hooks. The hooks are almost all the way down on the threads, but it's tight.

The other problem I encountered during this battery swap was that my negative cable connector was destroyed and the stock cable is too damn short to just take another replacement connector. So what I did was I got a replacement cable with a ring connector and attached it to the bracket on the inside of the fender where the stock cable is clamped down. The stock cable is like 2ga. wire and the replacement that I got is 4ga. The truck seems to be working fine now, but I'm wondering if this is going to be a good solution in the long term. Would I be better off getting a stock replacement cable? I want to be sure the the ground connection is strong and I'm not sure if that connector will cause extra resistance or something (I know little about electricity). Any comments?