Why do you want to pay for a project manager instead of a GC? They have no power over subs, and no accountability for mistakes. It costs you more in the end.

my friend did it and had a good experience. I don't think you save as much as you think. We looked into it as my husband is in a related field. But at the time it was near impossible to get on contractors schedules with a builder so we opted to go the builder route. He's had many life circumstances come up during the build and we are GC'ing many aspects of the project. So not sure how much value add he's given as we are finding some of the contractors. The ones he does use are great though. Hindsight.

So it depends on how much time you have, how organized you are, how many contacts you have, how busy the market is, etc.

I live on 5 acres in SW Okc. Go with a good builder. They will let you put sweat equity in where you want. It's expensive to pay a builder but their experience and knowledge of good subs was completely worth it for us. We loved our builder and he's now a friend.

If the idea of building an energy-efficient, air-sealed home is foreign where you plan on building, I suggest you consider a home constructed from pre-cut SIPs panels. Here's a link to a SIPs manufacturer in Tulsa, OK to get you started:

https://standardpanel.com/residential

Best wishes for a successful project.

To add: we have a very well insulated home. We installed geothermal and have a total foam envelope for insulation.