Several of my inlaws here in Vermont have built their own houses. But I’d agree with the suggestion that you buy some kind of trailer to live in until you get it built. Then you can sell the trailer if you want.
My son-in-law started by building a composting outhouse. Then he built a one-room bunkhouse with a crawl space loft and a wood stove. Then he had a place to stay while he built the main house.
You need to get the power and septic in, and I would check that. Also, I wonder if 5 acres is enough to plant on and graze animals. I’m not saying to buy more now, because I suspect that land prices will drop, but you may want to buy more in future if you can.
Also, don’t get trapped by the zoning laws or building code. Make sure that you are cleared for the septic or the outhouse. And make sure that you have a well for water.
Or if you have power you can do what I did on my old cabin that came with the place we bought. It was about 75 years old half log and the other side wood frame added later at some point. I had to install plumbing and figured the house was good for maybe a few more years. So I dug a cesspool and only ran the commode in to it. No one was ever the wiser.
Now I live a few hundred feet above where it was in a double wide. If times get hard I have enough land to live off of about 30 acres mostly woods. I could go out the back door right now and have fresh meat in short time. I've nearly ran over deer just leaving my driveway. Thankfully the home is paid for. I was criticized by some for not building a house. But I got a good size double wide on a 10 year note. 5 years into it I became disabled and unable to ever hold a job again. A wise choice that worked out for the best. We were able to swing the double wide payments but a home would have been at least twice the payments and on at least a 20-30 year note. It will last my life time anyway and I figure I may have another 30 years tops.
If this home became unlivable I have a 12X16 building beside it that would do nice till I addded on :>} One day work installing plumbing would have all creature comforts in it as well.
He does have one other option. Look for a used mobile home on the road he lives on that has the axles under it. They are dirt cheap as I sold one last year {12X60 still livable} for under $500. If really close by as in less than a mile have someone hook a farm tractor to it and pull it there. Beyond that though moving one around here can run several thousand dollars if done by pro's. Being rural has some advantages.