Can't help with your specific problem but once you get the filter off it might be worthwhile fitting a remote
oil filter if access is very restricted. If no one replies re volume of
oil put in 3 quarts then inch your way up adding a half quart at a time, giving time for
oil to reach the sump, say 5 minutes between each top up, until level is at the top of the dipstick. Then start it and run until oil pressure is up, switch off check level. Add more as required I would guess around 5 quarts in total will be needed depending on sump type. Rather under-fill a little initially than over-fill.