Level 1 won't keep up with the demands of the A/C, but no worries because the car can cool the cabin without being plugged in at all. Just use WattCat or the JLR remote app and set the cabin to precondition. It will run for 30 minutes. On the third party iPhone app, MyPace, there is feature titled Camper/Pet Mode where it will run the HVAC indefinitely (until the battery runs down). This is a lifesaver in the summer here in Fla. You only need to give the car a few minutes and it makes a huge difference on a hot day. For MyPace, there is a handy AppleWatch app that activates the cabin preconditioning with one click.
If you are low on charge and only have access to a Level 1 charger, go ahead and find a free level 2 charger in a free garage and get the kitty charged up. Level 1 is painfully slow.
For the rear climate, were you sitting back there, or trying to turn it one from the front seat? The car senses where people are sitting and deactivates zones where there are no bodies.