For racing, I run a 42:18 with a 1.75 rear tire.
That looks like a great park to ride. Have fun!
If you like the pump track feel, consider checking out a race track - there'll be a list of tracks at
USABMX.com - track search. Racing is a blast. I started a couple years ago at 40.
I'll note though, that even not having been on a BMX since the early 90s until I started racing with my kids, I far prefer my 20" to my cruiser.