What I do for water-proofing my bikes for enduros is quite easy. Clear airbox vent; freshly greased axles; lube chain, kick starter, pegs, folding tips, etc.; take two carb vent hoses and run up into the airbox (very important since if they all get covered the bike will stall, be sure not to pinch any in the process). Also remember when crossing water to not carry much speed through it since this could splash water in to the airbox on to the air filter and wet the bike out. Bring a plug wrench, extra plugs and plenty of paper towels in case the air filter gets wet. As long as you don't fall over into the stuff, you'll be fine, just take your time crossing it.