Q. We have cleared a 20' X 70'+/- area, that borders a Bucks County State park.
A Google search will give you many lists of deer resistant plants and native plants for Pennsylvannia. The Cornell list is excelent. Planting is best when avoiding peak sun shine periods. Overcast days are best.
Purchasing plants can be very expensive. Covering most of the soil with plants cuts down on the weed problems. Using mixed wild flower seeds might be the best way to proceed. Regardless of how you plant, after a few years different populations will be established at different times of the year. Some cultivars will not take. Breaking up the plot into different gardens might not yield the planned garden. Also, plants move around and spread seeds in other areas. Using a mix or different mixes across the entire area might be the best way to proceed. You can augment and move plants around once there has been a few years of growth. Another advantage is that having a wide selection of seeds facilitates establishing plants in areas with different culture requirements, sun vs shade, wet vs dry, etc. You can augment the seed mix with selections of seeds for specific plants and achieving some of the objectives you want. You will encounter plants that will dominate and force out other varieties.
Universities have done extensive work on establishing wild flower gardens. Search their web sites for information on their results. Cornell and Penn State campuses like Berks are good choices.