A Right angle pump head helps.. Got a pump without one?

You could use a short piece of high pressure hose ,
a valve stem from an old tube, a pump head, and some hose clamps
to make a pump like Lezine uses, for example
with a straight connection to the tube, work, without altering the pump itself.

there are some really nice right angle Presta Pump Heads, for disc wheel time trial bikes
just have a small hole around the stem , that is taped over during the race/time trial.