I think that around 0,5km it's possible to identify targets even without zoom in IL2 BoP.
Regarding other approach's to this problem, I seem to recall that in Combat Flight Simulator for the PC (
http://en.wikipedia.org/wiki/CFS1) , the plane models viewed from inside the cockpit where 3x the correct size to try to compensate for the Monitor limitations.
But all this happened last century and my memories might be a bit fuzzy...
(However i do recall my first successful landing on the Ark Royal
http://en.wikipedia.org/wiki/HMS_Ark_Royal_%2891%29 on this game.)