I've been leaving mine in the boot with boot open. General consensus is close boot. Now I've bought an extension I'll use it to travel from battery to outside, then CTEK to mains (if its long enough)

 

I had never seen my Ctek ever get hot to the touch but I had read of other brands that have heated up and short out. Because of this I had mounted an outside plug and kept the Ctek mounted on my metal lift. Just my personal taste.

 

I have my CTek mounted to a work bench on the opposite side of the XK.. The battery is on the left, the CTek on the right.

 

Lol, I wimped out on battery change and let my Indy do it at first service in Dec 18. Luckily I had a type 19 with high output in the garage which still had over 3yrs warranty left (taken from my old x100 that was written off). They didn't charge me for this.

As to CTEK I've always used an extension lead with it in the boot with tailgate shut and car locked*. The MXS 5.0 doesn't get warm on normal recharge only on recon mode.

*And yes neighbours have asked if it was electric...even with no backbox so it sounds like a diety gargling on startup

 

The guy in that video. He could be Rick Grimes little brother.