I'm jealous of your Net Zero house! That's been a dream of mine for a few years. By my calculations, I'd need about 20kw of solar (due to heating in Minnesota), so I have lots of work to do.
I think Nissan has targeted the 40kwhr Leaf at drivers who only need to travel about two "tanks' worth" (starting the drive at 100%, and then fast-charging only once during the trip). Even in my 30kwhr Leaf (without "rapidgate"), my charge rate slows-down noticeably on the 3rd fast-charge, after about 250 miles. Nissan isn't alone in this: Bolt owners have noticed throttling of fast-charge (even though the Bolt has a battery temperature management system).
It may help to look over the "range chart" for the 30kwhr battery:
https://www.mynissanleaf.com/viewtopic.php?f=31&t=4295&hilit=range+chart&start=450#p489173
I don't think Tony has made one for 40kwhr yet. But you can see that at 75mph, a new 30kwhr Leaf could drive 92 miles, but at 60mph could travel 120 miles. This means that if you need to maximize range, you probably want to avoid the freeway and drive the "old highway" routes. In a gas car, slowing to 35mph for each town hurts your gas mileage, but with regenerative braking, it doesn't hurt much. Gas cars have poor efficiency at "part load", so driving 60 vs 75 mph will only reduce fuel consumption by less than 10%. But in an EV, you get to realize the true efficiencies of slowing down, and save more than 20%.
Also, I'd suggest reading
https://cleantechnica.com/2018/07/22/2018-leaf-vs-long-journeys-best-driving-strategy/
...for clear graphs of how the battery temperature rises while charging, and falls while driving. The general advice there is that the extra time you spend driving slowly does triple duty: not only is it using much less energy ( so a longer distance between charges), but it also means fewer kilowatt hours of charging (so less heating-up the battery pack during charging), and the extra drive time is also "time well spent" cooling the battery, getting ready for the next charge. By driving more slowly, you can actually speed-up your trip!
Regarding heated seats, I added Sojoy SJ154A seat covers in the back, and found them to use less watts than our factory heated front seats, while producing more heat (the High setting is uncomfortably hot, except for a short burst of heat when you first get in the car). If you want to add four heated seat covers, you may need to run a wire directly from the fuse panel and not use the cigarette lighter. But I wouldn't worry about a lack of heated seats, because you can fix that.
Not having heated steering wheel is annoying (I wear gloves). Not having heated side mirrors is annoying when they get frozen sleet on them, and you have to chip at them with a scraper.
The heat pump is a funny one: as battery ranges get up to 60 kwhrs (e.g. Bolt, Tesla), many competing cars are not using a heat pump; people seem to put up with the reduced range. Would the extra $3k be better spent on the heat pump, or on a bigger battery? I think if you could get a battery which was 20% bigger at the same price as adding the heat-pump, then I'd rather pay for a bigger battery. Yes, you could heat with it, but in summer you could also drive with it.
Unfortunately, with only 30 or 40 kwhrs, I think the lack of heat pump is a bigger limitation than the heated seats/steering wheel/mirrors. If you are able to get Nissan to let you upgrade to the SL (or the rare SV with heat pump), I'd say "go for it." Or trade for a reservation on the 60 kw-hr model (reservations not available just yet, but should cost about $5k extra). The 60-kwhr model is supposed to have an unsphisticated air-cooled battery (similar to 2018 Soul EV and Ionic EV). That may not enable full-bore "road trip" charging, but should be an improvement.