I would recommend 3M autotrim spray adhesive as an alternative to sikaflex on the basis it is much less messy to work with and in my experince has been fine.
I've redone all my headliner twice. argghhh Both times with 3M spray adhesive but the first time with locally sourced vinyl. That gave up after a year in the tropics. The second time I used Naugahyde brand vinyl with non-migrating plasticisers. The problem with vinyl coming down is not just about the glue. The problem in hot weather is also the plasticisers in the vinyl migrating into the glue to turn it into a gooey mess. Naugahyde with 3M has been great for the past two years with my boat based in a hot and humid place with the deck often too hot to walk on in bare feet.
A previous owner of my boat did partial vinyl repairs with sikaflex and it was a total pain to remove.
My only caveat would be whether the original vinyl has fully non migratory plasticisers, which may be Phil's experience.
John, Maramu #91 Popeye