Sky @108k. Yeah maybe the shocks could be gone. 100k is a standard check point for all cars. I would say that the 75k-90k is about the right time to look in to replacing shocks & bushings during a suspension over view. You can push it here on the shocks, IF it ain't broke, don't fix it but they won't perform like new ones. Bushings could have taken a turn for the worse here too.
Tires, air pressure settings, rims, balancing & alignment. Two different sets of tires, although both seems to be new with tread wear life left, might be part of a harsh or rough ride. Air pressure settings, factory or by owners own personal choice to where they like their tires set at. Higher or lower will affect your ride performance, or lack there of it. Proper balancing and a 4 wheel alignment could fix some issues here. Toe/caster/camber could be out by the 100k limit. IF you have never done it, or the previous owner has not done this since the factory, IT might be time for this. I'm doing mine in the next month. Been 10 yrs. so while I'm in there for my fluid changes, just for my piece of mind and future reference on my car.
Sky & Ford Explorer... roadster vs SUV. Yeah low to the ground, short wheel base ride will not be like the Explorer ride. Every little bump in the road, bridge expansion joints, pot holes, road seams... nah I never noticed that.. well yes I have. Comes with the territory.
Backbone/Probeam could help some with roll stiffness to the chassis, but again here personal choice by the owner. Backbone can make a difference. Probeam gives it better handling depending on the owners personal choice. Harsher ride could be worse though.
Start cheap with air pressure settings. Then maybe balance/rotate all 4 wheels. Then alignment with maybe... hub bolts checked too? $ is the questions here.
IF that helps your good for now. IF not, then on to more expensive stuff. All four tires the same model make mfg. $$$ Then shocks & bushings= $$$. IF after that, you could consider $ for the backbone/probeam DDM after market add on parts. Up to you the owner, and your checkbook/mastercard. Depends on how much is your permagrin worth it to you?