I seem to be losing about a half quart an hour into the bilge and can find no obvious sources. The front of the motor is dry, valve covers dry, no residue on the breathers, it has a remote filter and cooler with push on hoses backed up by clamps but they are dry. I was thinking rear main seal but I can get my hand under there pretty well on the port side and seems dry. There is some oil on the starter mount area but that idea is pretty hard to get a good feel on.

Any thoughts?

Dumb question, but is there any sort of dye that can be put in oil to trace a leak?

YEs. NAPA and other stores have it. You usually need a UV light to see it.

check the rear of the intake manifold at the corners where it meets the heads....

Will do. Brand new top end though and it did it last season as well. I figured it was a loose fitting on the oil cooler set up but that's been upgraded as well. I'll power wash the mess and try the dye.

The dye will help you find it very quickly. In the meantime, can you get a camera or phone camera down there to shoot some pics. I use this method all the time.

You mention near the starter is wet. Could it be pushing it out where the dipstick tube connects to the oil pan?

What oil pan?

The little clip that holds that tube in is missing but the bolts pretty much hold it in place. Is it possible for that much volume to spit out of there?

I can't say what pan exactly other than its nothing special.

Does the motor have adequate or clean breathers on it? could be backing up some pressure or getting windage. I had a Mallory distributor plug/oil pump drive that had just a pressed in top cap. I was impressed at how much oil squeezed out of that cap to make a mess.