Hi - That is a tough one. Doing it from under the bed is a bit impractical, unless you are a 12 year old gymnast, and working from the access panel under the head of the bed is a bit better - but a little uncomfortable to be lying down on the bed frame and working with your arms in the tight access panel.
I've gotten into the area on our 24J by using the access designed to reach the water tank. That involves removing the mattress, and then removing all the screws for the mattress support at the head of the bed. That will allow the head of the bed to hinge towards the foot of the bed. That might give you more room if you can lie the head of the bed flat on the rest of the bed, after folding it over. If it doesn't fold flat because of interference from the window, like on our 24J, then you can disconnect the strut attached to the mattress support and move the mattress support around until it hinges cleanly. Or, at this point, you can just remove the whole mattress support. Then you can just "walk" into the under-bed storage and work away on the pump.
This method has been described for a 20 / 21 24J - if your View is a bit older, it might be easier depending on how the independent head supports work; I'm not sure of that.
Grandpa Ron shows how his works in this video, where he wanted access to the water tank. His View is about five years old.
Hope that helps, good luck.