Replying to Drop in help

Before i start, let me say that i SWEAR i searched for this, but i couldn't find anything that fit my question, i apologize if there is something out there. anyway, my bro and i built a ten foot long, 1 and a half foot high rail, and we need to make the drop in portable because we cant leave it on the lawn all the time. i was thinking about building something about 5 feet tall, but i dont know if that will give us enough speed. anyone have any input about this?