I think the thing is what you are looking for. On the Frances I enjoyed the camarederie of albergue life, it made it for me. I love camping, I camp all the time and it never occurred to me to camp on the Frances. It just didn;t appeal, there was hardly anywhere that was out of sight of
somewhere, always people around, etc. And to be honest, it's not the most scenic of trails either. When I camp it is very often because I want to be part of that landscape to enjoy it more, there was nowhere on the Frances that I really felt that apart from maybe the forests of the last couple of days.
Next week I start the Salvador and my tent will be with me. I deliberately looked for a remote walk and deliberately looked for a solitary trip. I fully intend to sleep under the stars
where it is reasonable. Any time I'm doing stuff like this my usual rule is to pitch the tent just before sunset and break camp just after sunrise (weather allowing) so I'm making as minimal an impact on the trail (and drawing attention to myself as little as possible). And where it
isn't reasonable I won't be camping.
As for sanitation needs, anyone who spends time in the wilderness knows how to deal with it again with little impact on the landscape. I think the big trouble on the Frances, going by what I saw and the disregard for the environment a lot of people showed, is that the majority of the people walking it
aren't generally outdoors people. They are just people who happen to be walking and don't have the skills or knowledge (and often the respect or common sense when it comes to landscape or water courses) that would be expected of trail walkers outside of the Camino.
This is a leaflet that is widely distributed amongst walkers in the Scottish hills and should be mandatory reading for everyone doing any long walk:
http://www.mcofs.org.uk/assets/access/where-to-go-leaflet.asp.pdf I think it covers, ahem, "practicalities" very well. I wish more people would pay it attention.
Weight of the tent... you can split it between two walkers very easily, it's standard practice. Or you can use ultralight or tarp tents that are very minimal. Or bivvy bags (I hate them). I carry cheap foam sleep mats on long walks. they are very light to start with but I cut them down to about 2/3 of the length and then trim it to an elongated ellipse as it's all you need. Very light, very compact. Or something like the Klymit X-Frame if you want an inflatable is very good. More than likely you'll have a bag anyway. So not a huge amount of additional weight. I wouldn't bother with cooking kit, especially as cooking outside can really get European cops backs up more than pitching a tent will due to the wild fire risk.