If a zoom/tele is too big, I definitely recommend a 2x Teleconv. for the 50 to give you 100mm, but at twice the focal length, ie: f3.6.
Good ones introduce minimal to no distortion, Nice and compact too.
No room for a small tripod? A bean-bag(rice or something) will allow some adjustment when sitting on a wall etc.
To give you an idea of what I mean, commercial ones are here:
www.cam-pod.com