It is a great site for all kinds of electric flight. Virtually every Friday afternoon, the grass area of the park aka Lot H, becomes an RC aerodrome. Many go there to fly their electric stuff, from quadcopters to T-Rex 3D helos and flying wings that are so overpowered that the motor is just as noisy as a glow engine,
The grass area could accommodate an electric CL plane provided it has the wheels and power to take off from grass-ithe grass in Lot H is smooth and short.
And yes, as long as there are no events at the Rose Bowl or the adjacent park (i.e. walk for autism, the UCLA games, lacrosse tournaments, youth and adult soccer matches et al) the park is good for flying. At times, I have been the only one in the entire park. On the other hand, at times the park is completely taken. This is especially true in the summer months, when the soccer clubs are active and use the entire Lot H.
The paved parking lot is great as long as there are no events and it is empty.
Oh, and no AMA is required to fly there. No club dues, no formal rules. I have seen RC pilots do things that could jeopardize this site.
Yes, ECL opens many sites that are off limits to glow.