I've considered similar approaches to the problem. One of which is getting a secondary "small car" to commute in, or perhaps a motorcycle to offset the fuel usage a few days a week. Then just drive the big truck when it's really necessary. Motorcycle has hiccups with logistics of 2 kids and needing pickup/dropoff/soccer/baseball/etc. Schedule will often not allow the time to return home for additional seats, and even if it did, most likely that moves some parenting logistics workload to the wife, and lord knows she does enough already. A second car becomes hard to justify for me as I'm right on the threshold of a reasonable payoff timeline. If I could "break even" in fuel savings in 3 years I think I would be happy with that setup. Then keep the setup for 5-6years total. At my mileage and the cost to get a reasonably reliable spare car for that time, it's hard to hit that 3yr window. If I drove more then it would be an easier sell......Plus then I'm paying for a nice 3500 pickup that just sits.
I've considered renting through a site like Turo, or Enterprise the few times a year we need that level of capability. But getting a hitch setup, and all that shenaniganery is going to be a tough sell for a 5th wheel. Large bumper pull, maybe, but even then it feels like a lot of hassle, although perhaps not as much as the cash I would spend on fuel would be?!?!
Current plan is to go back to tent/truck camping for this season. Make sure we really enjoy the "travel all the time" side of things. If that works out, we've discussed possibly getting a slide in camper for the 1500 truck so we can still bring the boat, or possibly just a large roof top tent. The big draws there are they get us up off the ground, provide a little insulation and padding for us, and with a slide in, some semblance of A/C in the summer. It kills me how much 1500 class slide in's are though. The Cirrus 620 we like is almost $27k. The GIANT 38ft 5th wheel we like is only $50k. Granted that's double the cost, we get almost 6x the interior space in the 5th wheel. A roof top tent, and supporting roof rack/bed rack is going to be in the $3-4k range depending on size/age.
Not sure where we'll land. I'm sure we'll know more after this summers adventures. If we really like travelling, perhaps the upgrade to a 5th wheel and 3500 pickup is worth it. If we don't, maybe we just buy the 5th wheel, have it delivered to the place we like, then build a deck around it and go there every weekend