engine is down and Winter is comming

So I have the top end of the engine broke dowm, and The truck is stored in a canopy type enclosure, with no doors on it, I have the intake manifold, watter pump, heads, fuel pump, power stering pump, timming cover and timming belts all off, and I sold the heads and wont be getting my other heads for a couple of months, I have the engine covered up as best I can and have been oiling down the pistons, I live in Mid parts of the state of Minnesota, and have mice and chipmunks running around, any advise on what else I can do to protect the engine,,,,Should I drain the oil out of the oil pan until I get things all back together??????

brakekleen the the block surfaces so duct tape will stick and duct tape and poly the top end up
Frank