How to generating a housing cost burden variable?

I am interested in using the 1-year PUMS estimates to generate a rental housing cost burden variable for metros in the U.S. What would be a good method for approaching this?

RENTGRS reports the monthly gross rent and HHINCOME reports total household income. You can capture metropolitan areas in the U.S. with the variables METAREA (available through 2011) and MET2013 (available from 2000 forward). You may be interested in this forum post about top-codes in RENTGRS as part of calculating rent burden.