I've got the oil injection location in the front cover to block, so maybe I'll just put a fitting in a cover plate and return it there. 

Last night I had a quick look at this, and I feel that there is almost no vertical drop between the RD-1A outlets and the injection oil pump fitting. As oil likes to flow down hill, this might not be to succesful. Routing is the other concern. I wouldn't want to route the line too close to the exhaust to avoid picking up any heat in the oil. The alternative is to go around the engine... also not very attractive. I like Tracy's idea of drilling and tapping through the foot of the end plate the best. You've probably already spent as much time thinking about how to avoid removing the oil pan as it would've taken to pull the engine and do it. (after the cowl is finished). You could drill & tap the hole, with a vacuum nozzle held right at the bit, then blow compressed air into the hole while vacuuming at the oil drain. Follow this up with a weak magnet (a strong one would just stick to the pan) on a wire that you could drag around in there. This should take care of everything and if anything was left behind, large chips would be stopped by the screen and anything smaller would be stopped by your filter before entering the engine.... however I d rather just pull the engine & pan to be sure.

That was the original plane.  Of course I am going to install a hose to the oil pan drain bolt anyway, just for oil change purposes.  

 I thinking about doing this too.

S. Todd Bartrim
Turbo 13B rotary powered
RX-9endurance (FWF)
C-FSTB (reserved)
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

        "Imagination is more important than knowledge"
                                        -Albert Einstein