Nothing I can help you with unfortunately but I’ll hopefully be starting out two weeks after you and would highly appreciate any updates on walking in Portugal during this time of the year.
I guess you’ll start in Lisbon given the time you have available?
As for 30€ a day - that’s around what I spent last year on the Invierno, Salvador and Primitivo. Staying at municipal albergues, preparing dinner myself, not drinking much in terms of alcohol or coffee (I don’t drink either anyway so that’s just a natural and easy way to keep the budget down). If you eat out often (especially if you want breakfast / lunch / dinner) you’ll struggle.