The Sea Eagles' back five looms as one of the most intriguing selection squeezes going into round one, with six men fighting for spots against North Queensland.
Hopoate played 14 straight NRL games after debuting as a little-known teenager last May, scoring nine tries and setting up seven others.
The vast majority of those games came while the Sea Eagles were undermanned, with Seibold avoiding a hard call for most the season.
Manly already have one of the most explosive wingers in the competition in Jason Saab, while Tommy Talau was close to the league's most improved player last year.
Saab has since battled an ankle injury throughout the off-season after having his syndesmosis ruptured last August, while Talau has also had ankle issues.
But Seibold confirmed on Tuesday that Hopoate would start the year on the wing, irrespective of availabilities.
"Turbo (Tom Trbojevic) will be our fullback, Reuben (Garrick) and Tolu (Koula) will be our centres, and then we'll make a decision on our wingers," Seibold said.
"I feel like Lehi Hopoate has done enough to be in our back five because he's had a good pre-season.
"We'll see out of Saaby, Tommy Talau and Clayton Faulalo who wins that last spot."
Seibold also indicated Manly were on the verge of announcing an extension for Hopoate, who is still on the club's development list this year.
Any new contract will accelerate his entry into the club's top-30 roster, and extend the son of John Hopoate's stay until beyond next year.
"Lehi is really keen to stay longer term and we are keen to keep him longer term," Seibold said.
"There will be some news in and around Lehi and his contract in the near future. He's developed a whole heap. He always had potential.
"Watching him in 2023, I knew he had potential so I gave him a six-week pre-season last year and he performed really strongly, so we extended it to a full pre-season.
"Handing a 19-year-old debut (against Melbourne), a lot of people probably thought we were crazy.
"But I thought Lehi handled that night really well and was one of the finds of the season in the entire competition."
Hopoate had told media earlier at the Sea Eagles' season launch he did not expect to start the year in the top team, albeit while more hungry than in 2024.
"I'm really excited to go after this year. I would say I am hungry, but it is a bit nerve-wracking as well," Hopoate said.
"Physically I am probably the same, I have only gained a kilo or two. But mentally I feel like my mental state of things is very sharp at the moment.
"We have a mental skills coach and he is helping me heaps with how to handle chaos and pressure."
Seibold also confirmed that Siosiua Taukeiaho would start in round one, playing his first game since the 2023 Super League grand final for Catalans.
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