RUM Specific Gravity

[sergiolis]

I'm just in my second generation of molasses rum, so just trying to get something decent.
I decided to go for Hook Rum but my proportion of molasses is much more higher than the recipe, mainly because here raw sugar is really expensive and in this case I paid even less for molasses than white sugar.
As HookLine points out trying to measure the specific gravity with a hydrometer is not very useful. However, I'm a bit confused because some of you talk about SG and for me it didn't work. So after the stripping run I checked the ABV of the low wines and then I could work out the SG of my worts.
Do you think this method is close (or acceptable) to the usual method using a hydrometer?
Thanks in advance