Clever! :-) But ... the TARDIS, cramped? Seriously? According to Wikipedia, the TARDIS contains:

... living quarters, ... a well-organised study ..., a swimming pool and bathroom, a sick bay, an ancillary power station disguised as an art gallery, and several brick-walled storage areas ...; a “cloister room”, an observatory, a library, a greenhouse, a baby room, a toy room and several squash courts. There is also a wooden-panelled secondary control room, and numerous other rooms .... The Doctor flippantly mentions a karaoke bar ...

Indeed,

In “Journey to the Centre of the TARDIS” (2013), the Doctor states that the TARDIS is actually infinite in size.

As for teenage girls — well, Elizabeth Sladen was around 27 when she first played Sarah Jane Smith, and Louise Jameson was around 26 when she first played Leela the savage. But yes, you’re right, middle-aged male Perl programmers probably shouldn’t waste their time applying for the role of the Doctor’s companion. :-)