Raymond Salu will make his starting debut at prop, with Kamipeli Latu moving to the bench ahead of Wiremu Cottrell.
Tyler Rogers-Holden again stretches his versatility, moving from halfback to the wing in place of Tom Symes, while Shai Wiperi switches from the midfield to fullback, as Troy Brown comes back into the side to take a starters berth.
This could yet change as the other winger in Vereniki Tikoisolomone has to pass a fitness test on his lower back tonght, or else Wiperi will full that spot and Clare will shift back to fullback, where he played on Eden Park against Samoa.
Karl Pascoe will be the new outside backs reserve, with Nick Harding on standby if Dane Whale has to start at first-five for Clare.
Hart's return to the blindside sees Samu Kubunavanua miss out as Chris Breuer remains preferred as the loose forwards reserve.
Caskey confirmed the reshaping of the backline, with potentially two regular fullbacks on the wings, was all about fixing up the lacklustre cover defence.
For the forwards, a good blowout at training was getting them in the mindset to get their feet over the ball, not their hands.
"Those set the standards at the start of the year about how many penalties we should concede and how many missed tackles.
"We had a bit of hard work to do.
"It's pretty simple, really, can't give away penalties that we have been giving away on the first couple of games.
"None of the [Thames Valley] kicks would have been 35m away.
"The last line of defence has to be a bit better than it has been."
First-five Regan Trosland's seven successive three pointers was a record against Wanganui in 130 games of Heartland rugby, and only the fourth time a kicker has slotted that many in the entire competition's history.
That is an ominous signal when playing a Buller team lead by the indomitable James Lash.
Trosland kicks were all in front or adjacent to the goal posts, while for a radar goal kicker like Lash, a penalty anywhere on the attacking side of the 50m line would be fair game.
He holds the Heartland season points record (147 in 2016, when goals only counted for two) and overall has scored 472 points in 42 Heartland games, including 24 points in the win over East Coast a fortnight ago.
Lash and No 8 Jeff Lepa return to the home side from the Eden Park game, although they will now have to go without talented youngster Caleb Aldridge, who joins the NZ Heartland XV Under 19's at the Jock Hobbs Memorial Tournament this weekend.
Lock Gabba De Kock scored two tries last week in the away game to King Country, but Buller certainly missed Lash's direction in their 34-12 defeat.
"They've been around for a little bit, those boys. [NZ Heartland reps] are not new to either team," said Caskey.
There are a couple more returns to the Wanganui side, as lock Peter Travis Hay-Horton has recovered from illness to take his place in the starting lineup, with Josh Lane moving to the bench, while Hay-Horton's Taihape clubmate Dylan Gallien finally makes his comeback as reserve hooker after the leg injury from the Division 1 club final.
Caskey did not take any changes lightly, as he is well aware that for staying in contention for the Meads Cup playoffs, three losses in a row could prove too much to absorb.
"We need points every week, and five is better than four, but winning is first up."
It is also going to be a long hike to Westport this time, similar to the 2013 trip when Wanganui lost 15-11 to the home side.
They were supposed to make a direct flight into the Buller district, however the runway at the home town airport is currently under repair.
It means an early departure this morning to fly into Hokitika airport and two hour drive up the coast by bus.
"So long as there's a TV on the bus that works," said Caskey.
Kickoff 2.30pm.
The Wanganui team is
1. Raymond Salu; 2. Roman Tutauha; 3. Gabriel Hakaraia; 4. Sam Madams; 5. Peter Travis Hay-Horton; 6. Campbell Hart (c); 7. Jamie Hughes; 8. Bryn Hudson; 9. Lindsay Horrocks; 10. Craig Clare/Dane Whale; 11. Tyler Rogers-Holden; 12. Troy Brown; 13. Penijamini Nabainivalu; 14. Vereniki Tikoisolomone/Shai Wiperi; 15. Shai Wiperi/Craig Clare.
Reserves – Forwards: 16. Dylan Gallien; 17. Kamipeli Latu; 18. Josh Lane; 19. Chris Breuer; 20. Dane Whale/Nick Harding; 21. Karl Pascoe; 22. Josaia Bogileka.