There isn't a lot of data on SLNB on thin melanomas between 0.5 and 0.75 mm. You should review the recent NCCN guidelines as well as the paper from Michigan regarding thin melanomas.
That said, it's debatable whether SLNB is "needed," as studies haven't shown any improvement in mortality w/ SLNB. However, morbidity is a different issue.
Anyway, this sounds a lot like asking for medical advice....so....mod?