Unfortunately, any marketing efforts to get you noticed are also going to require more investment money. You got 24 people to buy in so there must be some redeeming qualities for your location? If you are near the interstate highways, maybe some billboards to attract transients.
Others have already suggested Woodalls and similar publications. A WEB site always helps, but work to get your site up the ladder on Google so that it comes up easily in the area.
What's the attraction to your area? To your CG? Play on the positives!
Worst case, look to sell before abandoning the tenants you already have. It may not be the best option, but it's much better than closing the gates.
Paul & Sandra
Plymouth, MA
2014 Heartland Cyclone 4100 King