Hank, like Stijn noted, any survey tool that can maintain, or even simulate, a many:1 survey:lead relationship is going to require some level of development or at least what we might call "power admin." Even a tool that's been purpose-built to use a Salesforce custom object is likely going to assume you can create custom objects and get the possible technical consequences.
For a very quick-and-dirty simulation of many:1 without custom objects, you can store the lead's responses to multiple surveys in one big textarea using a standard format such as JSON, making each completed survey a sub-object within the field (literally a JS object). Using a webhook, you could intelligently append to that field. We sometimes do stuff like that to avoid the complexity of dealing with APIs. But it is custom development by definition. Or you could create a new textarea for each survey, which might even eliminate the dev effort completely -- but you'd still need to find a survey provider who understands that you want responses packaged as one JSON block.
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