you could include a number for each row that is printed (a small formula in the detail section like:
shared numbervar rowid;
rowid := rowid +1;
""

and reset the rowid in the page header...now change the color logic to reference rowid like:
shared numbervar rowid;
if rowid mod 2 = 0 then ...


since there is no data for the extra rows, there is no record number, so CR has nothing to work with. Creating a variable give CR something that it understands and can use regardless of dummy data or not.

HTH