Of 7 Predictas I have owned I have only once had to completely unwire a board...And I only did it because I wanted to swap a board with one from a parts set.
I haven't worked on a pedistal or holiday yet, but they look like they are probably a striped down Tandem...on my Tandems I figured out if you desolder, the ground lugs, speaker wires from the transformer and a ceramic cap that goes to chassis ground next to the H output the board will lift 1-2" enough to solder the bottom.
https://m.youtube.com/watch?v=1tsFuEi55ZY
The continental and the debutante chassis it's based on have a good number of holes under the board you can work from, and if those aren't enough you can lift the board by desoldering the ground stakes and unscrewing the V out transformer and maybe something else...Been a few years since I did one of those