I also gave the Idea of an extra port the chance, but my car's already 17 years old (hopefully it will reach an even higher age), so I don't want to "perform major upgrades" as I'm new to the "i'll do this by myself"-business (and would have to get a powersorce near the actual cigarette lighter, as there is quiet no electrical equipment in the car's ceiling)...
So hardwiring is no alternative... (at least in this car) So I'll go for the test as soon I've found the mini-USB-Cable...
i feel your pain on the old car angle. The a118 I own is in my wife's 2008 toyota sienna. However, my car is a 1998 toyota camry, which i also expect to last me several more years, and i have an f70 in there. i wired it different though, because back then i didn't know about those hardwire kits, and i happened to have a spare lighter socket that i could add. so i rigged it up so that the useless "sunglass holder" in the roof console now has an extra lighter socket inside, and i just use the power cord that came w/ the F70 and snake its cable out to the camera. of course since the f70 is a dual camera unit, i still had to run a cable around to the rear camera, but that wasn't a big deal, especially since my old camry doesn't have side airbags to worry about.
if i had known about the hardwire kit when i got my F70, i would have used one in my camry, too. would have been simpler, smaller, and cleaner since the new socket and power cord (and all of the extra wire, wrapped up), take up the entire sunglass holder. but since my sunglasses don't fit in there anyway, it doesn't bother me that the box is used up. but the main purpose was that i wanted to keep both of my lighter sockets free for use with phone chargers.
and if your USB adapter only provides 1 amp (1A = 1000 mA), i really doubt it will be enough to run a GPS or phone in addition to the dashcam. if the adapter provided 2 amps it would be fine, but 1 amp is pretty low current in terms of most devices these days.
also, you mentioned there's no power source in your car's ceiling - that may not be true. some cars had options for things like a trip computer or a sunroof/moonroof, and those are key-switched. even if the car doesn't have a sunroof, it may have the wiring for it already there in the head liner. it was there in my camry even though i don't have a sunroof, so i was easily able to tie into that for key-switched power.