There really is no point... and as you point out, it is better "serviced" by just pulling it out.

The interesting/ironic thing for me is that I was just looking at it... just thinking about it... building up the energy to remove it and replace the impeller.

I touched the back, where the plate is, under which the impeller exists... and a screwhead drops into my hand... as if the thing was saying... "yeah, service me now, baby." ~~ It was just uncanny timing. ~~

I've since removed it, cleaned all the mating surfaces, greased (with silicon) the gasket and the o-ring, as well as installed the new impeller in the proper direction. I found SS socket head cap screws to replace the old slotted head screws. I used TufGel and threaded these new screws in. I have now replaced the raw water pump, tightened the clamps for the hoses, checked for leaks, and run the engine... No problem. And having done this once, I think I could do it again in seaway, at emergency anchor, in about 45 minutes.

But no, I can't really work on it "in place."

But then, really, my biggest concern... are the hoses to the pump... either one could become stuck and difficult to work with. Maybe the best plan is just to get a second pump, have it all configured and greased up, and store it... with hoses. As it is, I DID store an allen hex key wrench with some spare screws and the impeller.