No need to do that. Fiverr was designed for smooth transactions. I’m not getting paid to print, scan, and share personal information like my name, signature, etc.
Whenever a buyer has questions about ownership, I just tell him that he owns the work he pays for unless he demands a refund.
For example, today a brand name client demanded a revision, and I gave it to him. That means the work I did before was no good, so I own it, which means I can buy one of the domains I recommended and sell it later. What I don’t own is the final delivery.
It’s the same with articles, logos, apps, etc. If they pay for it, they own it. If they don’t pay for it, you own it.