"They've just got to front, really. We've got some young blood up front - Jack Yarrall and that Kaierau boy, Josh Lane.
"Kameli [Kuruyabaki] and Poasa [Waqanibau] will be the midfield. That will be a lot of power there."
His own Waverley Harvesting Border loose forward Kieran Hussey will also want a big game "under pressure" to show he can handle Heartland level.
"[Caskey's] direction to me is, 'I want to see the guys I don't know a lot about'," said Williams.
Caskey acknowledged that while the trial may has moved from the traditional midweek fixture and therefore has no Premier games as an excuse, there will still be those players who cannot be bothered.
"If we end up with 40-45 [players], it might be that."
The game will be four quarters of 20m, with Caskey advising Williams and Thompson on who he would like to see go on to the field. There has been some good news - with key Ruapehu lock Nick Cranston making a welcome return to club rugby after missing the entire 2014 representative season with injury. The other position which needs attention is first-five, as from the 2014 playmakers, Taihape's Dane Whale has moved on and Taranaki import Josh Hamilton is not likely to be back.
"We're still looking, to be fair; it's to see what happens if anyone puts their hand up," said Caskey.
Also hoping the players take it seriously will be Hunterville Rugby Club members and supporters, who are hosting the game in a rare case of the trial being played away from Wanganui itself.
"They're pretty excited about it, and good for them too," said Caskey. "It won't hurt the other [Town] buggers to go over there, that's for sure."
Those invited to trial are:
Town (Metro): Jake Alabaster, Cole Baldwin, Isi Baleitavuki, Simon Dibben, Joe Edwards, Aiden Fitzgerald, Richard Graham, Manu Herring, Jack Hodges, Lindsay Horrocks, Bryn Hudson, Kieran Hussey, Taylor Kirkwood, Kameli Kuruyabaki, Areta Lama, Josh Lane, Kampeli Latu, Sam Madams, Ace Malo, Fraser Middleton, Marama Penetito, Stephen Perofeta, Apenisa Ratugolea, Cade Robinson, Sam Stewart, Clive Stowers, Kane Tamou, Meni Taufaasu, Viki Tofa, Brett Turner, Bobo Ulukuta, Lasa Ulukuta, Pene Ulukuta, Saene Vili, Poasa Waqanibau, Jack Yarrall.
Country (Northern): Jamie Brett, Troy Brown, Jackson Campbell, Nick Cranston, Matt Crawford, Jaye Flaws, Tremaine Gilbert, Tawhio Gupwell, Gabriel Hakaraia, Fraser Hammond, Zyon Hekenui, Johnson Hiriroa, Glen Horton, Jamie Hughes, Josh Hurunui, Marius Joseph, Te Tua Kemp, Samu Kubunavanua, Michael Nabuliwaqa, Brett Nicholls, Cole Paki, Cyrus Paringati, Karl Parker, Hepa Payne, William Short, Jordan Stayt, Kereti Tamou, Cyrus Tasi, Taylor Transom, Roman Tutauha, Malakai Volau, Rimu Wipaki.