I did not do a complete restart after keeping a FOWLR coppered (Cupramine) tank for the past 6 years.
What I did was used plenty of Cuprisorb and Polyfilters for around 5 months before I got some soft corals to try out.
It has been about 5 months since then (Nov 2019), GSP, Zoas, Xenia and Clove corals are growing.
Elegance, Bubble, Frogspawn, Torch and Blasto LPS are doing well.
Added 1 clam 1 month ago and it's also doing well, so i guess it is possible.