Playing fantasy permaculture polytunnels

I'm playing fantasy gardens at the moment and scheming out how I might lay out the interior of my polytunnel. Unlike much of the US I want my tunnel for summer heat - this will enable me to grow tomatoes and peppers, plants that would not be feasible outside here even in a 'good' summer. The tunnel will transport me to a true zone 9a perhaps :) as we rarely get penetrating frosts.
The thing is I'm not used to tricks to cope with hot dry climates so am looking for proven designs that I could consider using inside my tunnel - like a banana circle for example to create a nutritious moisture retentive area for hungry perennials (probably not bananas though - maybe canna?)

Banana circle in action

source

I have plenty of water, but will need to think of labour saving watering methods for the main beds - how to irrigate them? I'm certainly going to experiment with wicking beds as a raised beds along one side.

Anyway - has anyone got ideas of other things I can try?  Thanks!

I've made a big long list of plants and trees I would like to grow in my tunnel. I'm thinking of making use of the 'edge' principal to simulate a forest edge and have half the tunnel laid out like a forest garden with small trees and shrubs. The other half would be laid out for the annual crops like sweetcorn and tomatoes, that will appreciate the warmer climate provided by the tunnel. I'll probably have climbers like grapes across the width of the tunnel making use of crop bars for support.
The wicking beds would be against the rock bank on the uphill side and I'm thinking of a small (raised edge) pond in the middle of that wall. Both would be fed by collected rainwater from an uphill gutter. I'm wondering whether a tiny warm microclimate might be created between the wicking beds and pond that might provide a spot for something like citrus which would prefer even warmer winters than we get. I may be able to provide running water in winter which would keep it frost free in almost all currently likely scenarios.
Below is the possible layout. I'm looking for ways to distribute the water that would overflow from the wicking beds into the rest of the growing area. I've used leaky hoses before, but I'd quite like a plastic free solution if that were possible. I wonder whether some sort of leaky levada might work?