One of the reasons for looking at NiMh was not having to deal with the varieties of Lithium batteries. I have an area about 4.5" long, as wide as the tender, and probably over an inch high. The only thing in the tender is the speaker. The current one is a fairly tall one, I'd replace that with a low profile speaker for this configuration. It doesn't have to run all day on the batteries, but it does have to be trouble-free and not run the risk of creating a fire. I'm pretty sure I can get decent run-times out of NiMh for this first experiment.
As I mentioned in other threads, I actually have experience with several types of commercial (big) Lithium batteries, and when they get out of control, the results are spectacular and destructive! I have no desire to see that in my house! The one that exploded in a 10x10 test chamber and put the testing back a month to repair the damage was an eye-opener!
Looking at the charger, I also don't want to spend $175 for a one-off experiment in battery power, that's a non-starter.
