<font color="red"> The maximum operation angle is 25 degrees. </font>
I'm sure Jack will correct me if I'm wrong, but I assume that rating is for continuous use. Before anyone considers that as a serious limitation, I urge you to measure your slope(s). A brief tilt beyond 25 degrees won't hurt the engine, but I think I can guarantee it will get the operator's attention. 25 degrees is steep. You are likely to have traction and pucker factor problems before engine damage.
Jack certainly won't recommend this, but remember the ads for synthetic oil where they drain the crankcase and continue to run. With good oil, you can do that for quite a while - until something heats enough to cause damage. I've had engines run for a while on their sides, without discernable damage. The problem, of course, is knowing how long is too long, because too long is expensive.