What to use instead of academic 'we' when describing an experiment?
The use of the authorial 'we' is very common in academia even for single-author papers, as argued by many and properly referenced in the other question that you mention.

Personally, I would keep 'we' also for the thesis without bothering. I doubt anyone would misunderstand, but if you wish you can include a quick remark in the introduction: something like Despite the use of the 'authorial we', common in academia, this thesis is the sole work of its author. In many cases you are required to state that you are the only author anyway in some boilerplate forms in the front matter.

This looks much better to my eye than changing every sentence to a contorted passive form. Readability matters.