I did't use any P/E for this particular boat. Periscope housing is scratchbuild.
Periscopes made with 2.4 mm stainless rod, up to scale, in fact.
the business ends of periscopes are from the kit, attached with superglue and reinforced with 1mm brass wire.
insulators on wires are drops of cyan superglue.
all wires made with elastic lines, 1 mm for antennas, 0.5 for railing.
I still run experiments...