R. HaGaon Yaakov Moshe Toledano in support of pilegesh relationships.

B"H
Check out Yam haGodol by HaRav HaGaon Yaakov Moshe Toledano

Siman 75 approvingly talks about the pilegesh relationships as a possible solution to many contemporary halachik problems:
(Siman 75 is 15 pages long and starts on page Kuf Lamed Bet (132) [page 137 of the pdf document]):

http://pilegeshpersonals.com/Yam%20HaGodol.pdf

(I'd like to thank HebrewBooks.org for making this responsa available online: http://hebrewbooks.org/529 )

Anyone willing to take time to translate this well in English will have a great merit and will be amply rewarded with a year of free advertising here and a certificate for a full year of membership in pilegeshpersonals.com a total value of more than $200.