Hello captwho,
I originally grew up in Northern Wisconsin your ice quality is a large determining factor but as long as it isn't a refrozen slush from a thaw and refreeze. These are my recommendations I was always confident on 4" thick ice for playing hockey/ice fishing on and we would drive cars/trucks on it for ice fishing in 8" thick ice. If your pond is spring fed be careful though wherever the springs are the ice will be thinner. Hope this helps.
Here is a good reference too.
http://www.dnr.state.mn.us/safety/ice/thickness.html
In case you don't feel like following the link
This is from the house in Wisconsin.
Good luck, stay safe and if there is any question either stay off or keep a rope handy, also if you are flying solo a sturdy stick about 8' across can catch you if you do punch threw. It just gets really cold really fast if you do.
