[dsraven]

sounds like fun. (well, maybe not the oil filter part.
on my stuff I always weld a bung into the trans pan for future maintenance. I will make or source a thin nut that fits a standard LS engine style drain plug and drill a hole in the low end of the pan where the drain plug won't interefere with anything internal. some trans pans have the depression in them already where they would have had the drain from factory. then put it all together on the bench with the nut on the inside and a dummy bolt and a solid flat washer, instead of the normal drain pan plug with the rubber gasket, and tighten up the plug so the nut will be sucked down tight to the pan. then weld the nut in a few spots on the inside so it can't spin. then swap the dummy plug with the LS engine plug and you're good to go. this system doesn't fully drain the pan because the thickness of the nut doesn't allow that, but I am usually gonna be taking the pan off to change the filter and inspect for anything abnormal. it just makes way less mess and is easier than trying to take down the pan thats full of oil.
when I do the rear axle I always source a gasket first, then pull the pan off and drain the housing, clean the gasket surfaces off wtc. then I use a pump up garden sprayer that has viton seals to flush the housing with solvent, let it drain and dry. inspect the guts and then install the new gasket and clean cover. as a side note, the garden sprayer is a bit of a pain to always be pumping up so I drilled a hole the size needed for a metal tire valve stem and installed one so the cannister can be pumped up with the shop air line-gently-about 10 psi. it works great. I replaced the hose with some urethane fuel line used for sleds, dirt bikes etc so I have more reach and can see the solvent in the line.
anyway, sounds like you had fun. thats great.