Letters of credit will not get you community development loan credit. We (ISB) had gone through an exam with the FRB where we presented a letter of credit in support of affordable housing to LMI households and it got rejected.
Here's what the examiner commented: "letters of credit do not qualify as CD loans, however, special mention can be given in PE." Not sure how it will be mentioned in our PE. We have yet to received our PE...
Bear in mind that this varies from exam team to exam team. I would still write it up and explain in great detail why the project could not happen without the LC. Banks have received CD credit for LCs.