Need advice for 1-day Road Trip from Lisbon to Porto

I assume you’ve thought about what you’d visit at each of those locations rather than just selecting them out of the blue. The 3.5+ hours it will take to drive to Porto must be taken into consideration since it will cut down on your exploration.

Óbidos can be seen in a couple hours.
I don’t think there are large waves in Nazaré in March, but you can check that out.
You could combine Óbidos and Alcobaca Monastery since they are fairly close together.
Tomar is nice with the main draw being the Convent of Christ. You could visit the town and convent and skip Alcobaca or Batalha.
Coimbra is also nice with the main draw being the self-guided University tour. If you’re not interested in it, then you could skip it.

I know which I’d choose, but it isn’t my trip.

From your list , I visited Obidos, Coimbra and Tomar. If I had to choose from these 3, I would skip Obidos. ( I have visited other similar walled towns, not bragging, just saying!)
Now, choosing between Coimbra and Tomar is difficult, but if you are short on time, I would choose Tomar and save Coimbra for another trip when you can stay overnight to do justice to its sites.
The Convent of Christ in Tomar is spectacular! While the circular chapel was smaller than I expected, it was nonetheless exquisite.

If you go, be sure to leave time to walk along the ramparts of the adjacent Knights of Malta castle.
Also, for lunch Rick recommends Café Paraiso and it's worth a stop (for the atmosphere...food is ok) if you want a simple quick bite after visiting the sites. We enjoyed a light lunch sitting at an outdoor table with some locals. In terms of timing, we arrived in Tomar around 9:30 and left around 3:30.

Don't skip Obidos. Also, do Sintra. Nazare was nice.
Coimbra was good.
Also, loved our week cruise on the Douro River. The valley is amazing. If you don't take a cruise, take the train up the river to Pinhao and Regua.

Coimbre. The special, golden library. The museum of ruins. The hilly walk from the university down to the town. But I have not been to your other choices!