Persist across two different Virtual Servers - One HTTP-based the other not

Yes, it is possible to create persistence records from an iRule, either on it's own or associated with a Universal Persistence profile. I'd recommend associating the rule(s) with the profile, since that will allow you to use the 'Match Across Services' setting, allowing persistence to span multiple services, which is your situation.

You need to handle two different types of traffic, where some has an X-Forwarded-For header and some does not. Here's a link to an iRule that persists based on X-Forwarded-For.

For the traffic without the X-Forwarded-For, you'll need a rule that looks at client data, pulls out the significant information by length and offset, and then either decodes the client IP or determines it by looking it up in a datagroup (which is not a bad idea, provided the IP addresses used by your clients don't often change) and persists on the extracted/returned IP address.