Re: Coolant... seems regular antifreeze has it covered... and you can, in a pinch, add water... with this stuff you would be SOL unless you had more of it with you.
FWIW (cheap, unknown shipping $)
Military Ordinance Lead Battery Terminal Positive Post
Mil Spec: A52425-1
or
Zinc Battery Terminal - Military Ordinance - NOCO | Fisheries Supply
Complies with Military Specifications A52425-1 (MS75004-1) and A52425-2 (MS75004-2).
And once you get the specs for the stock struts you can go in and look to see if there is a strut with the same dimensions but with a bit more weight rating! But dont go too high or you will struggle to get the hatch closed!
Or look for ones that will lift the hatch a wee bit higher maybe...
I have ordered for other vehicles through them and it has always been right. Their customer service is great too so IF there was a problem you will have no problem. Use their online vehicle spec tool....
You are now talking about what, in my opinion, should be a more permanent, proper aux outlet install: Battery>fuse>wire (properly routed and protected) to rear location>aux outlet. Be sure to size your fuse and wire to handle the anticipated load. (this is the simple plan of course)