Oh, another thing I needed to address was the coolant.  The coolant that comes with the kit is Castrol Radicool SF, but that's impossible to find in the US.  My coolant was right at the minimum and I wanted to put some more in there, but I couldn't find any more of that particular coolant...

If you read about coolants and the Sling POH, you can't mix different types of coolant, so I wanted to make sure I got something that was completely compatible.  So, I contacted BP, the maker of Castrol.

They pointed me to Final Charge Global Coolant Extended Life, which they said is precisely the same as Radicool SF and can be mixed.  I looked at the specs and agree they're the same (they're both OAT-type and ethylene glycol).

Castrol SF-O (same as the SF)

Final Charge Global and more here.  I bought a gallon here and added some to the reservoir.