Study the 'Rear seal area leaks-Inspection' procedures on p. 9-217 here:
http://oskin.ru/pub/chrysler-dodge/manuals/Service Manuals/2000_R1_Dakota/ER1_9.PDF
The rear main seal service procedure is shown on p. 9-248. Does the flex plate appear to be flinging the oil around the inside of the bell-housing?
If the oil is too clean to see the definite leak source or leak drip/spray pattern, a UV dye and light can help make it more visible.
Interdynamics Oil and Fuel Systems UV Dye (1 oz.) 374CS: Advance Auto Parts
Be careful in diagnosing a suspect rear main leak. Many oil leaks can look like a rear main leak and it is usually the first thing people think of, but in the big picture, it isn't all that common. Of course with a lot of miles, anything is possible.
Oil will tend to leak downwards from gravity and rearwards from road draft.
The oil sender from up top next to the distributor is a common leaker. The intake manifold rear gasket is also common. Is it wet up there?
The rear cam journal soft plug at the rear of the block is less common, but still a possibility.
Try and determine the leak source first.

 

I'm afraid it will be hard to find the leak, the main reason being the fan sprays the PS fluid leak everywhere. I'll address that first then clean everything up.
I am glad you think it's a good chance the leak is elsewhere. Only 150k miles, not so many,

 

Agree with cleaning the power steering leak first. Heck, I've had valve cover and rear intake manifold leaks look like rear main leaks, so major investigation is is order.

 

Any leaking fluid "tends" to pool at the lowest point, and then drip off from there. Often the lowest point on the engine/trans is the bottom of the bellhousing (becoming less and less so in more modern designs). So, its easy to mistake the point where leaking fluid is collecting and dripping from as the source of the leak itself, when in reality it could be somewhere else because you're missing the clues.

Pretty much what IC and others said before, I had to add the collecting and dripping from the lowest point, to make sure if you hadn't consider it yet, you would.

It always help to thoroughly clean the engine, like spray it down with Simple Green or another De-Greaser, even scrub built up deposits with a brush and hose it completely, then let dry. With a shiny clean engine, that you check after each drive, its a lot easier to spot leaks at their source instead of their end-point.

The risk of washing out the engine is water in the ignition. Now with Distributor-Less Ignition (DIS) that happens even less. Even with a distributor it was rare and when it has happened to me, it was just misfires, open up the effected areas and let it dry out for a couple of hours; then it ran like normal.