I don't know if this is your person or not, but the only Alvin Comeaux I found born 1899/1900 is this one.

1900 CENSUS:

Alvin Comseux
[Alvin Comeaux]
Home in 1900: Police Jury Ward 2, Assumption, Louisiana
Age: 6/12
Birth Date: Oct 1900
Birthplace: Louisiana
Race: White
Gender: Male
Relationship to Head of House: Son
Father's Name: Alcide
Father's Birthplace: Louisiana
Mother's Name: Emalie
Mother's Birthplace: Louisiana
Marital Status: Single

Household Members: Name Age
Alcide Comseux 30 (farm laborer)
Emalie Comseux 31
Clefere Comseux 3
Alvin Comseux 6/12
Lenord Dramon 35 (boarder)
Edna Callagan 27 (Alcide's niece)
Marie Barras 75 (Alcide's mother-in-law)
Virginia Barras 20 (Alcide's sister-in-law)

1910 CENSUS:

Elvin Comeaux
Age in 1910: 11
Estimated birth year: abt 1899
Birthplace: Louisiana
Relation to Head of House: Son
Father's Name: Alcide
Father's Birth Place: Louisiana
Mother's Name: Emilie
Mother's Birth Place: Louisiana
Home in 1910: Plattenville, Assumption, Louisiana
Marital Status: Single
Race: White
Gender: Male

Household Members: Name Age
Alcide Comeaux 43 (married 14 years)
Emilie Comeaux 42
Claifoit Comeaux 13
Elvin Comeaux 11
Sidney Comeaux 5


1920 CENSUS:

There's an Alvin Comeaux born c. 1902 in Louisiana listed as a boarder living in Manhattan, NY, and this one:

Alvin Commeaux
[Alvin Comeaux]
Home in 1920: Police Jury Ward 2, Assumption, Louisiana
Age: 19
Estimated birth year: abt 1901
Birthplace: Louisiana
Relation to Head of House: Son
Father's Name: Aleide (Alcide)
Father's Birth Place: Louisiana
Mother's Name: Emily
Mother's Birth Place: Louisiana
Marital Status: Single
Race: White
Sex: Male
Able to read: Yes
Able to Write: Yes

Household Members: Name Age
Aleide Commeaux 50
Emily Commeaux 52
Clerfe Commeaux 23
Alvin Commeaux 19
Sidney Commeaux 16