When I first got my PPL, the flying club manager had me go pick up an IA to sign off a 337 on another aircraft. I was flying a well worn C-150 trainer. The flying club manager was a retired Navy pilot. And, the IA was also a DPE.
The manager told me to go fly and on my way back pick up the IA. When I saw the guy, he must've seen the concern on my face. He was husky, at least 250lbs. I shut down and he put the seat all the way back to get in. Then, slid it as far forward as he could tolerate it. Then, he said "We'll be just fine. Use the whole runway. Don't do any aerobatics. And, don't get too slow." We didn't climb very fast. But, we made it ok. I've never done that since.