Wicking Hugel bed experiment

We're creating a local Greenhouse Garden education component to a local park. A hugel bed being one of the features that will be showcased.
The soil in our area consists of mostly very porous pumice and doesn't retain water.
The hugel bed location allows for a 60 foot length.  My current experiment plan will be a 30 foot section lined with pond liner prior to adding the biomass base. A 1 foot lip of the liner at the center of the bed creating a 1 foot collection resevoir for that 30 foot wicking section. Any excess water collected would spill over into the unlined remainder of the conventional hugel construction.
Will we notice any diference in the sections of beds that capture water in the wicking resevoir?
Will we notice a gradient change from one bed to the other?
Should I isolate the beds completely?
Any thought before I jump on the skidsteer?

This seems like neat idea.
I would be tempted to use pumice,inverted buckets or something else to create and preserve a void that would serve as a reservoir.
Keeping the rotting materials of the hugel from filling it in would mean a higher storage volume.
A stand pipe for filling the reservoir and /or checking the water level might be good.

A good point William,. Dividing the 60 foot bed into thirds would allow the addition of a dedicated reservoir component. I wouldn't want to divide the experimental bed up any further than that 20 foot length.  I will be incorporating my water collecting beds from a greenhouse roof that I mentioned in an earlier post. They just delivered a 30x60 greenhouse yesterday. Looks like the weather may hold long enough to assemble the structure before we get any appreciable snow.