I have also never seen an A-7 with a Harpoon.

Maybe it is somehow connected with the technical issues - to launch
Harpoon, you would have to have a radar with an appropriate
air-to-surface range (an this one on A-7 did not look to have too good
range...)

But more probably, it must be a matter of division of labour in the Air
Wing - where anti-ship missions were belonging mostly to A-6E (or S-3)
rather than to A-7E, which was used mainly as a light attack aircraft,
with some emphasis on SEAD missions.

I really doubt if F-4 could ever launch Harpoons...

Just my humble opinion...

Best regards,
Jacek