Honestly, I'm surprised anyone's still asking about Clyde x Lincoln these days. That ship had its moment years ago on DeviantArt and FFN, but most of the good stuff has vanished as writers moved on or deleted accounts. There was this one epic called 'Phantom Reflections' that crossed over with 'Danny Phantom'—Clyde got ghost powers, Lincoln was the only one who could see him, whole secret identity angst thing. Pretty clever use of the source material's weirdness.
Last I checked, the author orphaned it on AO3 after getting flamed for not making it slashy enough fast enough. Fandom can be brutal. You might still find remnants on Tumblr blogs with broken image links. My advice? Search by the 'Author Is Dead' or 'Lost Media' tags on AO3, filter for 'The Loud House', and sort by kudos from like 2017-2019. That's your time capsule right there.
Don't expect polished prose. The charm was in the sheer, chaotic creativity of it all—middle-schoolers writing novel-length sagas between homework assignments.