Hallo Rachel,
no problem for the tip, unfortunately that archer lives about 500kms from me, and I can't see him very often

But another archer (my medieval archeology teacher, and the president of my medieval archery's company) taught me how to shoot in many different positions: from the back, lying with my back on the ground, with obstacles between me and the target... and so on!
I could try to share this knowledge, if you're interested, even if it's a bit hard to do that via web

Anyway, the 9th and 10th of July, we're going to commemorate a siege. The context is a National Park, in which, during 5 ages of researches, we've found about 36 castles, dating from Xth to XIVth Century, and we're going to use one of them as a background. If you're planning a trip to Italy, give it a try, we're going to shoot at long distances (180 meters maximum) against pottery, and it should be funny!
Greetings,
Mauro.