In the planning phase of starting a pool project...Looking at a 18x36 or a 20x40 in-ground liner pool...I do not want a deep end, but i want an over all water depth of right around 48". These kits come with either 42" or 48" walls...the way i see it, if i want a water depth of near or at 48" I will have to have a "cove" dug below the wall height of the pool no matter what wall i use...it is a 1500.oo add-on to add the 48" walls...why wouldnt you just use the 42" walls and dig out your cove to get the depth you are wanting (48" water)? Thoughts?