PTEROS - 10' Wingspan Foamboard Motorglider

The Pteros is the Photon concept blown up every dimension, with a 5' length, 10' wingspan, larger tail surfaces and more powerful motor. I had the parts in stock and wanted to explore the big wingspan thing, so I put it together. AUW 1390g or 49oz.
Keeping a 20:1 aspect ratio wing relatively stiff is exponentially more challenging, requiring 7 carbon arrow shafts instead of the 1 in the Photon. Being as it's what I had on hand, I used wing pairs having slightly mismatched chords. I installed the "nice" ones outboard and the "crappy" ones inboard, where most of the wing flex and other abuse occurs.
As you would imagine, it is extremely floaty and difficult to get down for a landing in a reasonable space. The spoilers help. I was flying a 2200mAh 3 cell with a 880KV 70g motor and 10x5 prop and getting 30 minute flights no problem.
I think I'd like to to adapt this to a payload-carrying design, which might benefit from distributing some of the load along the wingspan, like perhaps having twin motors, outboard batteries, etc.
I take my hat off to those who entered the "Longest Wingspan Contest" a few months ago. All of their planes were larger than the Pteros, and were surely a challenge to build!
My son is into dinosaurs lately, and the Pterosaur, Pterodactyl, and Archeopteryx gave the inspiration for the name.