Small Engines (Lawn Mowers, etc.): gas lawn mower for steep terrain, 4 stroke engines, self propelled lawn mowers

Question
What are the recommended gas self-propelled lawn mowers for steep terrain?  Almost all available mowers are 4-stroke with gas and oil separate.  Do any mowers have oil pump to circulate oil even if mowing on a steep pitch, no matter which side of the mower is higher, or which end if mowing straight up a hill?

Answer
20 degree angle is about the limit of 4-stroke engines.  There are a couple with pressurized lubrication that advertise you can go to 30-35 degrees, but this is only for a few seconds.  Most, if not all, the 2-stroke mowers have been eliminated because of EPA and CARB restrictions.  

And of course you run into the safety aspect where the mower might flip at extreme angles.  

I think your best bet is to try and find a used commercial Toro with a two-stroke that has been taken care of.  I'm afraid a lot of our options have been taken away.