I tried the Sopwith Camel package here -->
http://simviation.com/1/search?submit=1&keywords=sopwith_camel.zip&categoryId=As you said, it's a tad frisky even with the Aircraft Realism set to Easy. After a bit of messing around I realised how this was done.
Find the [WEIGHT_AND_BALANCE] header in Aicraft.cfg & change this entry
empty_weight_CG_position =1.395, -0.57, 2.37 //2.95, -0.37, 3.37
to this
empty_weight_CG_position =1.395, 0, 0
This tweak should make the Camel a lot more docile, even on the Hard Realism setting, but it won't be realistic.
Please note that I'm not saying this is a general fix for the other aircraft you mentioned. The flight dynamics for each one will be different. Most experienced FS developers go to great lengths to make their aircraft fly as realistically as possible.