I would purchase as large of a fyke net as you can afford and hopefully you have some friends/family willing to help you set it and pull it. You can really hammer crappie numbers with a decent sized fyke net set and pulled often. Particularly in the spring months when they are shallow...

Hammer the snot out of your crappie with the fyke net, hit the hard with angling and consider stocking advanced sized HSB. If you don't feed the fish in your pond, the HSB should be that much more effective. Limit the amount of structure and particularly vegetation for the crappies to take cover in and see how that goes...