that trip looks like it was a blast! Having the dogs along must have been fun as well
I’ve done a fair bit of unsupported unicycle touring, though never off-road. I found that for distance a geared 36 is the weapon of choice for me, since it cruises so well on pavement. I find that while it is a bit sail-like, I’m willing to take that tradeoff for the ability to do consistent 100km+ days.
That is pretty independent of your issues with the seat though. There are a couple of coping mechanisms for saddle soreness that I tend to use, and in order of effectiveness they are: moving weight off my back and onto the uni, using a handle (like the kh t-bar), wearing bike shorts, and reducing my load overall.
I have always in the past tied my sleeping bag, sometimes my tent or tarp, some of my food and water - basically all the heavy items - to the rear underside of my seat. This is really uncomfortable if you don’t have a good handle, because it pulls the seat back into your crotch, which sucks for obvious reasons
Once you add a handle though, you can lean into it (or put counterbalance weight off the end, I know benoit in quebec keeps his food attached to his handle) and this allows for a couple of different riding positions so you can move around when you feel sore, as well as put some of the weight into your arms.
Finally, I’ve been slowly changing my camp kit to the best ultralight versions I can find that still work for me. You can get sleeping bags and tents in the 900 gram (2 lbs?) range, eat lighter, make your unicycle lighter, etc. This one isn’t as high on the list because it’s expensive! But it can really help you out to get the right gear.
One more note on seats - I tend to use stock KH seats but I’m about the same size and weight as Kris, so I bet we find the same things comfortable. Seat preference is very different based on the person and what works for one may not work for another. Keep trying until your butt is comfy! And of course, putting 30 lbs extra on your seat is going to make even the coziest seat feel like a pile of thumbtacks after a couple of hours, especially without a handle to distribute the weight.
I hope that’s helpful! All the best in your future trips, it really is a great way to see the world.