This will play an important role in our search for territory but I think it is manageable. We can build a lot of natural gas or mineral oil pipelines with lengths up to several thousand miles. For example, the 1200 km-long north stream gas pipeline from Russia to Germany was not built because there were no other pipelines. No, there are two more but the companies wanted to be independent from the interests of neighbouring countries.
Most dry areas, even the centre of the Sahara desert, are no further than 1500km away from the ocean. The distance from Zacatecas in Mexico and the gulf of California is 300 km, which is almost no obstacle to our aims.
There is a seawater desalination plant in California supplying 3 million people with drinking water, costing 2 billion dollars.
There is also a solar power plant nearby Las Vegas with 400 megawatts of power that can be used to deliver the energy for desalination, costing 2 billion dollars.
A pipeline (now used for mineral oil) costs 2 billion dollars for 1000 km.
On the other hand, space travel agencies plan to spend up to 500 billion dollars for sending a few humans to Mars to cultivate it. We can cultivate the desert on our earth to much better conditions.
Here is a calculation for the water demand of a territory.
Is a central wastewater treatment necessary? There are well-developed compost toilets. And there is a spacious area to seep away the grey water for use through irrigation.
How should the state authority be established? Should it derive from the host territory or is it possible to establish an autonomous authority within the area?