I, personally, won't jack the car up by any point other than the tire jack points. Others will know more than I about where else you can safety jack the car up.

However:
There is no reason to jack the car up to change the oil. My current Roadster (an SE) did not have the splash guard, but my Graphite did. I fixed this issue about the third time I changed the oil. DO THIS:

• Grab a small 1/4" rachet with the proper socket on it and lay next to the car and remove the rear screw from the under-engine splash guard. Go to the other side and repeat this.
• Go to the front of the car, lay down and remove the two front screws.
• Pull the splash guard out from under the car, use a sawzall to cut it into three parts.
• PLace all three parts in the trash.
• Slide a low-profile oil drain pan under the car, remove drain bolt, drain engine.
• Put drain plug back in.
• Grab the four screws that held the splash guard in place and put them in the trunk - they are the same size as other screws in the car and make nice spares.
• Pull the filter carrier out, replace filter and o-rings, pay attention to the diagram that came with the filter, position the BIG o-ring as shown in the diagram.
• Pour eight quarts of 5W40 full synthetic in the oil filter cavity.
• Put filter/carrier assembly back in and hand tighten.
• Start engine, if oil leaks from around the filter carrier, you didn't understand the diagram.

This can be explained via one of two explanations:
Some here drink a lot then post on the forum.
and.................
Some here drink a lot then READ what is on the forum.