of course apply for the visit visa its not a lot to risk or lose.
i don't know if telling them that you cant get your wife here because you cant apply for a spouse visa is a good idea thou,thou honesty is usually the best policy

if you did get your wife here and she overstayed i would have thought UKBA will make it difficult for your wife to get any legal status in the UK, probably refuse any visa applications you make.

thou if she was pregnant and the child was born here, then she might be granted what use to be known as discretionary leave, but that means if i remember correctly its 10yrs on FLR before she could get ILR .

so try the visit visa, if she gets it make sure she goes back within the 6 months, i don't think its worth the time, money and stress if she overstays, wondering each day if you will get a deportation notice