Perhaps you can get an inline hose one and put in the lower hose near the block
Mine started without doing anything after 3 days on cold for here nights and 25 degree days ---with a 10 year old battery made from 1/2 of a 12 volt battery
drain the oil, warm it up,put it back in, have a fully charged warm battery
take one of those electric hot air heaters and let it blow on the engine for a while
If you start it run it until the oil is hot to evaporate condensation ----otherwise it is best to leave it unstarted till you are ready to drive,