Looks like you all have the majority of this covered. I would only suggest two things;

1. Use three or five gallon buckets rather than rubbermaid tubs if possible - much easier on the back.

2. I wouldn't worry too much about trying to save all the old tank water, and as Rob said, I would have new water premixed and heated at the new site if possible - "old" tank water doesn't really carry much besides the chemicals, and so long as you have the new SW mixed to the same parameters as the old, saving the old water isn't all that important.

Good luck - hope all goes well.