hi ferrisjo!
Just wanted to say that i'm almost in the same situation,couldn't make it to apply for my desired schools in the second round.
I'm also from a very underrepresented country and have a unique non-traditional background + Interesting work experience as a founder and manager,although i'm not very happy about my academics.
It's difficult to get admitted in R3 not only because you must have a very good profile but also because you're an international student and admission committees are well aware of the lengthy process of getting a US Visa.
as far as i know,Some schools like booth encourage international applicants to apply in round 3 as well and clearly state that there is enough time to get the visa too.
however i'm still not sure if i should go for it and apply in R3.
BTW,forget about HBS and making a call for round 3,its no joke!even if you had a 780 GMAT Score and were applying in R1,your chances of getting in HBS was below average.
its not an easy task to get into a top school at all,even getting into a top 25 needs considerable hard work and persistence,no matter how unique you think you are and how great your GMAT score is!
everyone here will tell you that you have to take the application process as serious as you can!
ok i hope someone can help us with some clear answers brother
:D