How to best balance SalesForce "requirements" with UX best practices in contact/chat forms?

In developing some new contact us and chat (non-gated) fields, I'm finding that when I meet SalesForce "requirements" the fields are a UX nightmare.

I'm ending up with a minimum of 5 fields, and with our other (legal) requirements, the module is ending up at a stupid height of over 768px.

Required: - first name - last name - email

Optional: - Phone - comment/subject

All with their respective required or not natures indicated as they fill out the fields (no asterisks, etc). Sales is telling me they can't process leads with the preferred unified name field. Can I bring any ammo to the table to say how awful and cumbersome this is, and how we'll have higher bounce rates? I've told them those things and they don't care. The reason for the name separation and email req. is for case-linking—for existing accounts in that case—as well as lead gen.

I also want to remove the phone number field whenever chat is online, and keep it when they send a general contact request when chat is offline—if there's any validity there, but I'd like more business-y reasons instead of "UX doesn't know anything" "excuses" I keep giving them.

Thank you.