Have not seen anything mentioned about this more 'utilitarian' option available for the C7.
Paying $100 for an automatic battery maintainer (ERI)... specifically designed (?) to plug into the rear accessory power port on a C7 seemed like a good idea. That would mean to me, that it's been well thought out and ready to go (that's why I ordered it, while I already had two battery tenders in the garage). My suspicion is, that no one tried hooking the thing up (prior to production), in the fashion that most Corvette owners would use it. The power unit has two holes in it's base, obviously designed to fasten the unit to a wall next to your pride and joy. Thought this was a great idea! Made a one foot long wooden mounting pad to put onto studs in the garage, so I could attach to the wall next to the hatch. Power cord was of sufficient length... but the cord from the charger to the car was not quite thought though. They must have forgotten that owners who 'rest' their cars during sloppy winter weather (all of you in the northern states and provinces know who you are)... use a CAR COVER (mine is a 'dust proof', from California Covers). That cord, when plugged into the car, and draped out from under the bottom of the cover, means that the charger body has to be within about two feet of the car... this had me mounting the unit about ten inches from the floor, with a loop of wire about six inches off the floor. If that sounds like a tripping hazard to you... you are right. After snagging myself three times walking around the car, I remedied the problem by splicing in about five and a half feet of additional wire. Now I've got the unit up at around four feet (where I can easily see the charge status over the car) and have the cord to the car laying flat on the garage floor (no longer a tripping hazard).
Used 16 gauge stranded wire, wrapped, soldered connections, and used shrink tube on the joints and then larger tube over the whole thing. NOTE TO GM: Increase the length of the charging cord by at least five feet.
I could pass as an electrician (although worked in mechanical/piping system design for about 42 years), but not as an electrical designer... so I'm just assuming I've not affected the operation of the charger (in some crazy 'impedence' kind of way, or something).
I had a thought after all of your input. I am considering leaving window down slightly and running cord out over drivers window. This will be a safegaurd for me to keep me from getting in and driving off with charger connected. I will make decision once the extension arrives and I hook it up.