Weight and balance calculator
Click on this link:
RV-12 W&B Spreadsheet
CTRL-S will download the Excel spreadsheet. I forget who the author is.
You and your son-in-law will be within weight and balance limits. If max weight is not exceeded, the next concern with a heavy pilot and passenger is exceeding the forward CG limit when fuel gets low. People sit in front of the wing spar and fuel is behind the wing spar. As fuel is depleted, the CG moves forward. If the CG is too far forward, the airplane will still be stable in flight, but it might be difficult to flare for landing.