I'm still looking for ways to smooth out levodopa levels. And via the original paper, found this thread from 4 years ago.

Here are the pharmacokinetic parameters reported in the paper:

V = value
U = units
A = initial situation
B = Plantago ovata husk
P = placebo

V, U, A, B, P
TMAX, min, 35.83, 39.72, 36.17
CMAX, ng/ml, 603.2, 547.8, 612.0
AUC, ug.min/ml, 62.87, 64.47, 65.10
THALF, min, 75.2, 81.9, 74.0

So, any effect here is small and probably not statistically significant. But, nevertheless, it's probably a useful area for N=1 trials: you might be able to squeeze a 10% increase out of your levodopa by optimising its use in this way.

John