Need a second thought should i tryout for football in my local area?

Well before you ask no this is not like high school/collage/middle school football. This is for a minor league pro football. I am not a spring chicken any more and i have hand knee injury's from when i use to play. I played all threw grade school 4th grade till i was a Senior in high school. Now i am older and just saw they are starting a minor league pro football team and a buddy from high school who also didn't get a football scholarship is talking me in to going and trying out because i was a bit thing in high school. But now that i am older and settled down and have a daughter i put on 30 pounds, i am 6'3" 261 pounds, I told my wife and she is suggesting against it for the main reason if i get hurt more in my knee's i might be in a wheel chair (i already use a cane at times). This league also pays there players and it would always be great to have more money coming in and me having fun at a sport i use to play. Am i keeping this boyish dream alive for no reason and thinking of my self? Is it smart to go back at this age,(i am under 30 years old). What do you suggest?