It is good to read that you are planning on a Solo Wilderness Retreat. Everyone has their own way of doing that. Some people rent a cabin for a few weeks, or backpack into the wilderness. A backpacking Solo Wilderness Retreat can be as easy as taking public transportation to the end of the line, then hiking off from there into a place of solitude in the wilderness.
About 40 years ago I took a free bus to the end of its rout in Santa Barbara, CA, USA, and camped in a quiet place by a creek. There I also spent a week camped on a rocky ledge above high tide, just on the edge of down town. There was a free kitchen that served the poor there. In retrospect I think I should have just stayed there all of these years.
About 10 years ago I drove a van into the Inyo National Forest for the better part of two years, but I could have just as easily taken the bus to the end of its rout and hiked into the mountains that surround Tucson, AZ.
About 40 years ago I found great efficacy in spending an entire year sleeping under the stars. Then I found so much inspiration in it that I thought I would never sleep indoors again. However, over the decades I have had so many large predators take an interest in eating me, that I can no longer meditate or sleep comfortably or deeply on the ground. So, the van has become my retreat refuge. At the depth of meditation that I have gotten to now celestial phenomena has simply become a distraction anyway.
On a Solo Wilderness Retreat one does have to figure out water, food, and shelter. In the case of a Solo Wilderness Retreat in the mountains that surround Tucson, AZ there are plenty of springs, and creeks that run year round with relatively pure water. And, I had considered them since my interest in a Solo Wilderness Retreat began when I was 6. Back 40 years ago I invested what little money came my way on good quality backpacking gear. Some of which I still own and use.
However, the problem of food had always been an obstacle for me. Canned food is heavy, so one could not carry much of it in a backpack. Which means back packing in and out of the wilderness great distances on a regular basis was completely unrealistic, as I realized I would spend all of my time and effort schlepping food and water back and forth from town to camp.
So, back 40 years ago, some money came my way, and I had supported myself cleaning out stalls at a nearby ranch, and irrigating the pastures there. So, I got to know horses, and felt comfortable with them, and thought I could buy a horse and go further with it. I soon realized that I would need 2 horses. One horse for me to ride, and the other horse for packing gear.
Among the things about horses that drew me was they just eat grass and weeds, so they really do not need to be fed. And, they live about 30 yeas, and reproduce themselves, so I could own a male and female pair of horses, and end up with a small herd of horses, but then I would end up being a full-time cowboy. I also realized that it would take me days to ride a horse from the edge of Tucson to the nearest grocery store just to feed myself. I also did not feel comfortable leaving my small herd of horses tethered on the edge of a city while I went for food.
Hunting and fishing would solve the problem of having to come in and out of town regularly for food. But one would have to learn how to hunt and fish without any modern equipment, because having to come into town for bullets, and/or bate, and hooks, still posed an obstacle. Also, I learend in the Inyo that one cannot eat meat or fish alone. For health one must eat some vegetables, so one would have to learn ow to forage as well, which i learned.
My conclusion 10 years ago was living in a van that I could fuel from dumpster-dived waste oils, and living in the wilderness on the fringe of a small town, where I can get waste oil for fuel, and food bank food, and is surrounded by wilderness, remains my prime focus. This is why I have chosen Prescott, AZ, USA as my home-base.
The same lifestyle could be done on a small boat that is paddled, and/or sailed. Bolinas, CA, USA is a place that would work for such a lifestyle.
Another option is a fully equipped touring bike. I have the fully equipped touring bike, and it remains my back-up plan, but I am getting too old for peddling great distances with a load of food and camping gear.
I hope these thoughts help.