So if you only need a non-EV a dozen times per year, have you considered renting for those trips? You can rent a small (but decent) car for about $30 per day. Assuming each of your long trips was for two days, that would run you about $600 per year in rental fees. Whether or not fuel savings the rest of the year would offset that cost depends on many, many factors. Of course, this assumes that you have a car rental location within driving distance for your EV, but unless you're really out in the sticks, you probably do.
on top of which it's extremely expensive for what it is
Perhaps. I find that I really *like* driving an EV. The relatively high acceleration, especially off the line, plus the silence -- and the ability to warm the car up with the garage door closed on a cold morning -- are nice. I enjoy driving an EV more than I enjoy driving a combustion-powered vehicle, which is worth something to me.
I should mention that I own two vehicles. One is an EV (Nissan LEAF) which we use for running around. We live 20 miles from town, but it has enough range to run into town, do some running around, and get home. If we absolutely need it, there's a quick charger in town that we can use to "top up" to get home. 15 minutes there gives us enough charge to get home, but it's rare that we need it. My other vehicle is a full-sized pickup truck (Ford F350) with a big diesel V8. We use that for hauling stuff, towing stuff (boat, tractor (on flatbed trailer), camp trailer, etc.), tooling around in the mountains, etc. We sometimes use the pickup for long trips, but usually if we don't actually need the pickup we rent a small car. It's cheaper than feeding that big diesel (which gets 15-19 mpg).
My LEAF is leased and the lease expires next month. I normally buy vehicles and drive them until they die, but EVs were new enough that I wanted to be able to walk away. I think we're going to go test drive the Chevy Bolt, and if we like it we'll get one of those. We like EVs, but would appreciate just a little more range than the LEAF gets us -- to ensure we never have to stop at that quick charger.