I love this tank design.
It will be interesting to see how the foam holds up to salt water.
I have used this type of foam on many home projects. It holds up pretty well over time. It will become dark yellow and brownish over time. It also turns brittle, but it does not break off on its own.
I have never seen it used this way, so it may be a hit if it all holds up. I think once it becomes populated with organisms and coraline it will be fine.
I want to also say (not wanting to start this again..but) that your skimmer is under rated for the size of the tank.
At BEST, any skimmer on the market is overated by 2X. As someone else previously said, it will function, but it will not keep your tank as "clean" and nutrient free as it should be.
What this means that your Nitrates and Phosphates will raise quicker and to much higher levels, since your skimmer will not be "pulling" out the organic waste matter at the rate it should.
The results of this will be the typical algae manifistations along with all the other "fun stuff"
"The reef aquarium Vol 3" does an excellent job of expalining this in detail.
Increasing the flow rate to the skimmer, does make the skimmer more efficient or increase its ability for waste removal. Thats not how it works.
There are several very good skimmers in the market that will do an excellent job in handling your tank much betetr than the one you have.
Again, this meant to be a suggestion from someone who learned about this the "hard way"