Lay irrigation supply line in the eaves strip?

We are currently preparing the garden landscaping work around the house, and since we have a cistern, I wanted to lay the water pipe from the cistern to a few tap points at the same time. In our specific situation, we have to go around the house to be able to water both the front yard (near the cistern) and the main backyard.

Is there any technical/practical/logical reason against laying the water pipe (DN32, PE100 RC planned) in the eaves strip?

It will be implemented anyway and runs roughly along what would be the ideal path for the water pipe. I have to dig about 60 to 80 cm deep for the eaves strip, probably half filled with sand, fleece, and gravel on top. So I could just lay the water pipe on the trench bottom and save myself the separate effort for a second trench.

Or is it a completely stupid idea?

Works without any problems. You can do it like that.

and of course save me the separate effort for a second trench. Or a totally stupid idea?

That is a good idea, then there is no path over the pipes in case you need to access them later.

We have done that too. You actually don’t need to go that deep since you have to drain the line before winter anyway regarding [Endpunkt / Übergabe] or how have you planned this?