No need to infer. Stormy Daniels slept with him and wrote about it:

“He knows he has an unusual penis,” Daniels writes. “It has a huge mushroom head. Like a toadstool … I lay there, annoyed that I was getting fucked by a guy with Yeti pubes and a dick like the mushroom character in Mario Kart … It may have been the least impressive sex I’d ever had, but clearly, he didn’t share that opinion.”