I had done exactly this on 10.09.2016. I had my 10m vertical wire dangling down from the middle of the platform and two radials spread over the floor of the platform. Here are pictures:
I was aware, the metal staircase and the lightning conductors would eat up most of my 10 W from the KX3. But why not try out, what will happen?
40 QSOs in 31 minutes calling CQ and another two calling other activators for S2S. Seems enough HF escaped this trap. As I wanted to activate the near castle ruin Weissenstein, I packed up after 45 QSOs including 2m FM.
I had done exactly this on Platte, also. I affixed my pole at the bench near the hut and the lookout tower on 29.08.2015. Again the 10 m vertical wire with radials for 40 m and EFHW on 20 m. 21 QSOs on 40 m, 4 QSOs on 20 m and 8 QSOs on 2 m FM.
So the summary:
Do not care too much about the attenuation of the trees or even other obstacles. Just set up your antenna in the usual way and see what’s happening.
By the way: The wind generator on top of the lookout tower emits nasty QRM on 2 m. So not a place for 2 m SSB 
73 de Michael, DB7MM