In the past few years I have also discovered this information which you may or may not already have.
The Middletown, Monmouth County 1830 census records a number of Crawford households. I suspect the Gilbert recorded is OUR Gilbert but have not learned any way to sort the families out, as they only identify household members by age, race and sex.
Gideon Crawford (Note: probably not Gideon of Freehold, NJ who married Helena Taylor)
William J Crawford
John J Crawford
I have also learned that Gilbert and Amy had another son (in addition to William G Crawford; Mariah Crawford; James Gilbert Crawford; Sarah Crawford; Rulliff Crawford; and Amy Van Kirk) named Daniel Crawford who died 19 Nov 1869. He was single and his occupation was Shoemaker.
This is very interesting to me because his brother William G Crawford is recorded in the 1870 census as a Shoemaker or Boot Shoe maker.
I wonder if this was the family business?