POG rules question & terrain making

[pyrrhicvictory]

Recently I have been inspired to build some more trench systems and this in turn made me read through the Price of Glory rules again.  This got me thinking, should shell holes count as 'difficult terrain', as my shell holes are quite deep (I think about 3/4 inch deep, but I haven't measured them.  Also, I am still looking to build more board sections, and was wondering about dugouts.  At the moment I have a front line with two saps heading to the rear.  All of my dugouts are located along these saps.  Problem is it takes ages for the troops to move to the firing step!   Does anybody with more knowledge know how dugouts were incorporated into the front line trench?  I could post some photos of my 'slice' of Verdun if anybody is interested.