Service department at dealership yesterday said they hooked up laptop and it showed everything was fine. I asked for a printout showing capacity, but was told there was nothing to print out. I went up to Service Director who is investigating this further and supposed to call me back today.
It is typical for dealers to not be aware that there even is battery capacity information. But if you tell them what I said, Electric Powertrain page, look for Battery Pack Capacity, you should get better results. If they still question this tell them to look up Honda Service Bulletin 17-093 which covers PDI items for the 2018 Clarity, on the last page is where it tells them how to check the battery pack capacity. Actually ask them to print the page showing the Battery Pack Capacity so that you will have a copy.
As for not seeing very many Clarities on the lot anymore in Arizona, after 2018 Honda pretty much stopped shipping Clarity outside of California. They exist outside of California but not very many and are relatively hard to find. Many theories about why this is, the most likely one being that Honda makes little if any profit on the Clarity, combined with it being in a category of vehicle (PHEV) that few people seem to know even exists, and with continued low gas prices there just isn't much interest right now in this type of car, although I think there eventually will be.
As for compatibility with Arizona, from what we know the Clarity battery management system is quite sophisticated and includes battery cooling, however this is only available while the car is running or while it is charging. If the car sits for hours in direct sun in a parking lot in 105 degree temperature that makes things somewhat rough for the battery, but we really don't know how much if any harm that it actually causes.
Besides high temperatures, another thing that is believed to be bad for battery life is for the battery to be charged to 100%, made worse if it sits fully charged for a long time. Now there is a lot of debate about this as critics of this idea point out that 100% on the gauge is not a full charge, as there is a sizable buffer left on the upper end specifically for this reason. However there is a lot of evidence from battery experience in other electric vehicles that although the buffer helps quite a bit, keeping it charged less than 90% (probably around 80% actual charge) helps even more. And that would seem to be especially true in hot weather.
But for Clarity we really don't know whether this helps or not, or whether it is worth giving up some EV range just for a theoretical extension of long term battery life. However many people's charging habit is whenever they arrive home they plug in and immediately start charging to full, even when they know they won't use a full charge the next day, or they don't expect to even drive anywhere the next day. Maybe that's fine and makes no difference, not enough data to prove one way or the other. But I suspect that this method, although certainly the easiest, may not be the best for battery life, especially in a very hot climate. Unfortunately to charge less than 100% you have to use scheduled charging and estimate all of this yourself. Although using the app works well for me and with a little practice it's not that bad. What I do is if I am pretty sure that I won't need a full charge the next day, I charge to about 85%. If I guess wrong and I drive more than I expected, oh well I burn a little bit of gasoline. However when I know I will use a full charge I do charge to 100%, but I set the timer so that it reaches full less than an hour before I plan to leave. Maybe you already do all of this but if not it's something to consider.