I have given it some thought and if I was only doing this as a car-camping/weekend sort of thing where weight is not an issue it would be a slam-dunk to add a pad or SPE of some sort.
However, this is for my thru-hike beginning in roughly 59 days and while the additional weight of a pad is not prohibitive the bulk is. In other words, if I pack the sleeping bag (my over quilt), the hammock and underquilt in the pack itself I have taken up better than half of the space inside my pack even compressed down to the smallest size I can get them. Mounting the pad and hammock, in the skins, on the outside would be the smart thing to do.
Again as most everyone who regularly hikes knows weight and balance of the load are important aspects of comfort along the trail. And while my plans are going to be pretty flexible. The plan right now is to carry the max food I can so that I can stay on the trail longer instead of just two to four days worth (NOLS among others recommends for my weight 2 to 2 1/2 lbs per day) and having to waste time repacking and packaging food stores, standing in lines and the sometimes long detours off trail that occur because the nearest full service town is more than a couple of miles away, hitchhiking several miles there and back, and there is no guarantees that you will get a ride one or both ways though the odds are fairly weighted to the 'you will get a ride' side.
Having had survival training and being a hunter I could set snares for fresh meat along the way but this means being static or staying in one place for a period of time. Then there are the edible flora and fungi along the trail that I can collect. ( Not everyone should attempt this as it is relatively easy to get very sick by eating something that looks safe and really is a false safe looking food. Not bad in and of itself but then I do want to at some point finish in Katahdin preferably in the same year I started.
So from my own perspective and remembering HYOH principles I am now refining my gear and useage issues so that surprises are minimal starting in March. It's good to be home and test things where you can bailout safely to the house. I'm definitely not going the Ultra-Lite route but am following the credo, 'Minimum weight, Maximum Gain'.