I don't think the rack needs a ton of lubrication, its not like its a bearing surface spinning several thousand rpm under load.
And it'll have a film of lubrication in it at all time, because you aren't draining it out fully you are just removing the pressure from the rack so that it doesn't lock up from fluid pressure.
Another option would be to create a grease zerk out of the old line fittings by silver soldering or brazing a zerk fitting into the fitting, squirt a few pumps of grease into both sides and work it in back and forth for awhile. Don't know how stiff this would make it, probably better if the rack was worn badly but most boats have greased steering cables, same thought basically.
I'd stick to the first or making a loop, don't feel the loop is needed if you lock to lock the rack a few times to remove excess. If you want to have the rack full then the fluid is probably needed.