The military draft is not as you say “unconstitutional”.
What IS unconstitutional is a forced conscription (draft) targeting men only which was on February 2019,ruled to be unconstitutional.
Since women are currently exempt from registering for the draft that would have to be amended with the passing of a law by Congress.
AS for what I am thinking by my suggestion, that would be to force if necessary people to pay back this country for all they have had given them while living inside it’s borders.
You said “instead of a draft we should have mandatory service”. Thats forced labor. What were you thinking?
Have you served?