Since my mother tongue isn't English, I wanted to be sure what "prolonged bars" mean.
So I guess the best answer is "no, but you might get by with it"?
I don't think bar-ends (where you mean extensions that are attached to the ends of a flat handlebar) are illegal, since that isn't the same as aerobars.
Aerobars were considered illegal in PBP because they can be unsafe if used by in a peloton, and thus the insurance carrier for the PBP doesn't want them used. Bar-ends on a flat don't have the same safety considerations and I imagine that they should ok, but we should perhaps wait for someone who's actually ridden PBP to chime in.
Aerobars are banned in all group rides in France because that is part of the road rules, it is not PBP specific.
The way the PBP rules are written and the response Audax UK got when they asked the ACP this specific question about 8 years ago was that all bolt-on attachments to handlebars were banned. Nonetheless, riders with flat bars and barends passed inspection at the two PBPs I've done.