If you can find a log with enough diameter to get a few rough-cut pieces the size you need, clear of sapwood and heartwood, take it to a local sawmill and get it cut a little larger in all measurements than you expect to need for the final dimensions. Allow at least a year for the rough-sawed wood to air-dry, then get it planed to final size. The best pieces will come from a "clear" section, with no knots or serious checks or cracks. I floored a 16 foot utility trailer with 3" thick rough-cut hickory almost 20 years ago, and it lasted until last year before it needed replacing. I don't pamper my equipment, so it saw about 18 years of hard use.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!