Steve, I just did a vintage combat wing. The older giant triangle style wings. The center section is very abrupt in terms of coming off of the sheeted area and onto the sheeted trailing edges. Ultracote stays down far superior without the void over the Monokote. I won't say that it was perfect, I will say it was the next closest thing.  It was like night and day. I personally wouldn't two piece it. It just makes a haven for dirt to collect revealing the seam and eventually or possibly a seam failure. You would even be surprised how much oil can wick into the pin holes as mentioned. For the look your trying to achieve and the durability, I would suggest Ultracote and I'm a dyed in the wool Monokote user.