I used to live in that area, but didn't buy until I moved to a lower COL area of FL. Here's my $0.02.
People that rent by the week or month are usually incredibly needy. Incredibly. If you can't accept calls when the internet goes out (have you calculated adding utilities and bills like cable and internet for short term rentals? You'll need to cover them) or stupid stuff like that at all hours, and can't afford to pay someone else to manage it and take those calls for you, I wouldn't go that route.
You should be able to look your property up at the Dade County Property Appraiser's site:
http://www.miamidade.gov/pa/property_search.asp From there, you will be able to see how much your homestead exemption is decreasing your taxable value for the various taxable districts. With that, you should be able to interpolate how much taxes will go up on the house when you switch your homestead exemption to the condo. (Since at that point Market value will reset to assessed value and assessed value can at that point start increasing 10% per year as long as it's still less than or equal to market value.)
For flood insurance, do you know your flood zone classification?
If not, you can find it by going to the FEMA website here:
https://msc.fema.gov/webapp/wcs/stores/servlet/FemaWelcomeView?storeId=10001&catalogId=10001&langId=-1 Use street address + zip, then on the next window, you want to "retrieve printed FIRM panel" and then click the little magnifying glass icon to view. It annoyingly opens up a lot of new windows in your browser, but the info is all there. The areas are shaded showing the different flood zones.
Being coastal, you're most likely AE EL #, where #, the number, represents how high your base level needs to be above sea level in order to qualify for market flood insurance rates. If you had a survey done when you bought the property, your survey will tell you what that base elevation is. Otherwise, you can call around and get an Elevation Certificate done for $70-$100.
If your elevation is over the # in your AE rating, then you are already paying market rates for your flood insurance and you shouldn't need to worry about crazy increases. If your # is under the AE rating then your rate will increase, and the FEMA site had information on that which I can't find right now.
You might be surprised. I just looked up Surfside and it says it's an AE 8. That's actually pretty low (we're an AE 10), so you might be close to having market rates already (I say never having been to your house). The map was updated in 2009, and isn't scheduled for another update for at least 5 years or so I think. So those flood zones should be stable for the 3 year window you're considering for riding appreciation before selling.
Anyhow... If I were in your shoes, I'd look up those numbers to see what the impact on taxes and flood insurance will actually be, and then see if you can make it work as a long-term rental. With a full time job, I know I would hate dealing with the neediness of short-term renters.