I would continue using my CRM (Pipedrive, btw), with a different pipeline and different follow up rules done by you or another partner.
Also, create a marketing funnel to nurture these special audience with prime content to create a relationship with your brand. For that, I use a marketing automation software here in brazil. Just like Hubspot but waaaay cheaper.
To track social, you could use tools like hootsuite or tweetdeck and set alerts and a column with their profile activity so you can use any opportunity to a positive interaction with them.
Hope it helps.