The 23-year-old utility back, whose proposed move to Hull fell through last year, is two-thirds of the way through a trial spell with the Rhinos and boosted his chances of securing a permanent deal with a two-try display in their 40-26 Boxing Day victory over the Wildcats.
"That's put him in a strong position," admitted Leeds coach Brian McDermott.
"You can't be signing blokes on how they train but he has done everything asked of him so we were leaning that way anyway. That's now put him in good shape for when the decision comes."
The Exeter-born Vickery, who scored 17 tries last season for Gold Coast Titans' feeder club Tweed Heads, seized his chance while deputising for an ailing Ben Jones-Bishop, touching down twice in the opening quarter while playing on the wing, and he looked equally accomplished after switching to full-back.
Fielding just three members of their Grand Final-winning team, Leeds' makeshift team ran in eight tries to five against a Wakefield team forced to play with 12 men for an hour following the early dismissal of new signing Justin Poore.
The Wildcats also lost second rower Lucas Walshaw with broken ribs while hooker or half-back Kyle Wood is set to miss the start of the new Super League season after undergoing surgery for a detached retina.
The 23-year-old former Doncaster, Sheffield and Huddersfield player, who was an ever-present during his first season with the Wildcats in 2012, suffered the injury during a training-ground accident.
"He got a stray finger in his eye," explained Wakefield coach Richard Agar. "It's a blow because Woody made a lot of impact last year and he's been going great in pre-season.
"He's had surgery and will be out for two to three months, maybe even longer."