After reviewing the thoughts above, my advice would be to follow the KISS principle: Keep It Super Simple. After you experience your first FIRST season, you'll have a better idea of what you need vs. what you want, vs. what you can do. If anything, go really light on the sound system. If you're too loud, the pit bulls get after you.
Seriously, a 'little red wagon' can do the job adequately, even though it doesn't look too cool.