Well I'll go ahead and answer my own question I guess for posterity...
98 Explorer EB 4WD. I ended up ordering the new power mirror off eBay with heat and light (even though I only had the puddle light on my old one) as I figured I could make the electrical connector work even if I had to splice it. To make a long story short the electrical connector was compatible and the mirror works fine. I now have a heated mirror as well as a bonus as it appears the electrical was in place for it in my EB.
Ordering the part off eBay
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was painless and cheap ($21 USD + shipping!) so I'd definitely recommend them. Replacement was easy: - Remove inside door panel (with window down) - 2 screws and some push pins - Remove speaker to disconnect mirror plug behind it - Remove 3 bolts holding mirror on (don't drop them in the door!) - Reverse above