"Alternatively, on future wells it might be worth checking if it...

"Alternatively, on future wells it might be worth checking if it is possible to drill, log and case the upper half of the well in the 8.5" section, then drill the lower half using a 6" bit followed by hole opening (under reaming) to 8.5" hole, run a slimmed down version of the MDT or equivalent through the 7" liner to access the open hole section? Having a cased off section over the PA and UA would help minimize logging problems over the LA."

The MDT can be run in 6" hole with a slimhole kit but with a hole prone to mechanical deterioration the much smaller space between tool and borehole increases risk of getting stuck. There may be one or two slimhole formation testers around but I doubt they'd have the same capabilities as the MDT. For pressure only work another option is Slb's PressureExpress tool which can be run with other logging tools. Ive run this tool on the bottom of a supercombo tool string.