Have room for a 5-gallon bucket somewhere? 6-10 hours of sunlight? Good.
Plant your tomatoes in 5-7 gallon buckets or containers. They’re not pretty, but white painter’s buckets can be purchased inexpensively from any hardware store. They’re light (an important consideration for roof deck gardening), cheap, and reflect the sun’s most brutally hot rays.
If you live in the greater Philadelphia region (or are a zone 7ish gardener) Anytime between May 10 and mid-June will probably work for planting your crop. Nurseries and farmers’ markets are still selling plants so get going. (Try to find plants without any blossoms — fruiting takes a lot of energy and transplanting large plants can be fairly traumatic. To the plant. Not you. The plant will be better off in the long run)
Save those evil Styrofoam pellets and use them as a drainage layer. (They’re light and it’s gratifying reuse of a non-biodegradable material — you can even save them for use the following year.) Or, you can break large pieces of packing Styrofoam in more manageable pieces. A 2-3 inch drainage layer seems to work pretty well.
If your plant is small (say, 5-10″), bury 60-75% of the plant beneath the soil line. This will make for a much stronger plant. Snip the leaves that will be buried before submerging them in your clean, organic soil. If your plant is pretty well-established (as most are by now) you just need to make sure you nestle the plant deep enough into your container that the new soil line at least matches the existing one.
Stake them. (see RIP Poblano)
Hope for the best.