Is there parking at Loeb Boathouse for diners?

No

There's no driving into the park anymore let alone parking an auto. Best is to find parking near 72st Eastside area and walk at that entrance into the park. It's about a 15min walk and if you have a wheelchair you can easily go through without stairs. It's a lovely walk. From the westside it's a longer walk but it's quite pleasant if you find shade while walking. I didn't need reservations on a Saturday but I did wait 10mins at noon. They have 3 menus on a weekend, Brunch, Lunch, and Dinner. There's a set 15pct tip applied on the check, fyi.