Long distance trip - need your advice please

Definitely break the trip each way into 2 segments. I'm an old guy that has routinely done 700+ mile runs in a day (but without a trailer). When RVing and just wanting to make mileage I would run around 400 miles a day. You need to run a little slower (105 kph for your rig). You need some setup time for your rig, some daylight play time for the kids and some winding down time for you and your partner. Don't overextend on your first trip and make it a miserable experience for the kids.

I can relate to your quandary. When on a limited time, sometimes it really is about the destination. And often you have already seen most things within a days drive and you need that long full day push just to get to new territory. When I was a kid my parents took us a lot of places, and for longer trips usually day 1 and the last day were looooong driving days to get out of the local area and to get home. We also did not have the benefit of electronic entertainment!

You know your kids and family best. How do they do on other long rides? Some kids travel well others don't. Either way everyone will need to stop and stretch every 2-3 hours. Eight hours is certainly doable, 16 not so sure, you will have to make that call. Good luck and enjoy your trip!!

We travel back and forth from PA to FL (~1000 miles), both with and without the RV, and always break it up into 2 days. It is safer and there are plenty of campgrounds where you can enjoy a leisurely evening and let the kids burn off all that pent up energy.

Find several options at different points in the drive (8, 10, 12 hours) so you can play it by ear. A place with kids activities will make the drive bearable for the little ones!

Split the trip even more...drive 5 hrs. a day.
You said you had little ones (2 & 5). Even 8 hrs. driving is too long especially with the set up and take down involved with camping and a pop-up.

Your "little ones" will hate it.

With children that age, I would stop after 8 hours, unless of course they will sleep through most of the trip.

Or, find a nice camp ground en-route about half way and spend a night.
Maybe in an area with some type of attraction that you & the kids would enjoy.

Best part of RVing is taking your time! It's about the journey, not the destination. Is it better to push through and arrive exhausted, or break the trip down into smaller bites that allow you to stop, relax, and arrive refreshed? My own personal rule is 300 miles or 3PM. When I hit either one of those, I'm thinking about where to stop for the night. Just my 2 cents...