Last night, i was reading part of a toddler book on 27-28mth olds. It said to let the child have the tantrum (although, do what you can to avoid them...) Dont give into the desicion you made if a tantrum occurs. While the tantrum is happening, make sure the child cant hurt herself by moving away objects, pillow or jumer under her head if she is hadbutting the floor or wall, dont pick them up or hold them - this will make it worse.
The important part i took from this article was "once the tantrum has stopped, continue on normally as if the tantrum never occured". That way the child learns "nothing changes with that behavior".
i think if i had of waited at the park for dd to finish her tantrums, i would have been there untill dinner time. it did take 45mins of tantrums back to the car :/
i guess i did the right thing by not letting her go back to play once i said it's time to go home.