If possible Marc I would suggest that your friend take a look at an '07-'09 model.
Reason being that the '05 and '06 were first 2 year models and they do have some issues.
By what I can tell most of these issues were addressed in the later years.
Just ask me, I found out really quick. lol
Nothing here that cannot be fixed or prevented but it would be better to go for the later year ones, IMO.
Now if for a specific reason your friend really wants an earlier model year tell him or her to pay attention to the passenger footwell as they usually leak there and rust (defective gromet on firewall, blocked drain or windshield issue), also inside the truck, usually in both side pockets but for some reason worst on driver side (trunk welds or leaking tail light). Spare tire area often show issues as well coming from same source.
But the worst issue is that the roof brackets were very weak and are prone to break, these were revised in '07, '10 and '14 according to the parts guy here at the local dealership so '07 brackets are better if my info is correct ?
And by the way you are probably way more informed on this than me, but just in case that convertibles are not your thing I figured I would put this out if it can save your friend a few headaches ? Other than that once things fixed they are fun cars and I do love mine.
Like you say, happy cruising and hope he or she finds a good one and enjoys it.