If you do not plan on boon docking or charging while driving (not sure why you would do that) you could always install one of the 120volt outlets that have the usb ports built in. They do not cost that much and work great, I have installed many of them in customers homes.
An iPhone charger is 1 amp. iPad charger is 2 amps. An iPad will charge on a 1 amp charger but it takes more than twice as long. I've never understood that.
PSI and CFM if you wish. Think of filling a tire with one of those mini 12 volt compared to a shop compressor....it will do it, but you'll be waiting 30 minutes. The shop compressor will do it in seconds.
I have 240 watts of solar on roof keeping a pair of Trojan batteries totally 225 amp-hours charged every day the sun shines. Haven't worried about power since. I just top of the battery cells every few months with distilled water. Cargo trailers have plenty of roof space so it is easy to put it to use.
I use the 2 port USB chargers that fit in the lighter sockets.