Coming from a tiny track, with an even smaller paddock, let me share an approach from Waterford Hills, which seemed to work:

We used a 'nominal' fee ($75, which went to the club, not the track) for assigned ANNUAL paddock spots, and limited the number of assigned spots; key thing, we had a 'general admission area, but it is called 'swamp' - you make the logical leap of faith. The key aspect: we marked the pavement specifically at widths - each person had a paddock number, and the spot was 20x18, for tow vehicle (trailer OR tow, not both!) and race car - NO EXCEPTION. That is enough room to paddock! The key thing I noticed this past year at Lime Rock was poor usage of space, total lack of policing excess vehicles, and not really a lack of good, quality paddock. Drainage will always be an issue when you look for a large FLAT region separated with pavement. Sorry!

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Dave Youngren
NER ITA RX7 #61