yep that is a bad place for it to break.
can you take the outer clip off and push it in far enough to turn it to the (take apart point?)

can you get the part of the axle locke in a vise or weld a big nut on it? then your bolt Idea vs drilling and taping?
that Inner c clip is kind of a biach to break. or can you push the axle part in far enough to pry the clip off? just a thought if you can get two really small screw drivers in there.
or grind flat spots and try the vice.. and a big pry bar if you can get it locked in the vice.
or weld the broken axle back on and remove with the pipe method that you mentioned.

sounds like you have enough and room to weld a bar (weight),rest of the broken axel, on to the stub.. then go from there.
so do you have a welder? or some one to weld on a big nut or the axle to it? if not then it sounds like alot of drilling.
good luck.

edit.......
I would weld the old axle back on or a chunk of rebar then do the pipe drop method.
that is a pipe that fits over what used to be the old axle vs the wieght that you welded on and slam it down on the pavement or cement to get that little chunk out of there.
I just ordered 20 of each of the axle clips from marlin. I just can't find them local. or they wanted fricking 7 bucks for the one that you are trying to break. marlin they are like around 1.50 each.