It is best to rent a car for this trip as public transportation is limited in the area. A standard car rental for five days will cost around $200. The estimated travel time for the whole trip is around 20 hours.
If you have more time, consider visiting the Buzzard's Roost Trail or the Irwindale Speedway. For those who have less time, you can cut down the beach day or skip some of the historical sites.
The nearest airport to Baldwin Park is the Los Angeles International Airport (LAX) located 35 miles south of the city. Another airport option is the Hollywood Burbank Airport (BUR) which is located 25 miles to the north. However, it only serves limited domestic flights.