Buy the started plants and save yourself all that trouble. It's way too late in this zone to be direct seeding those plants. You won't get any fruit from them till late summer and fall!

Many of the varieties I have are early maturing (50-65 days for the slicers and cherry tomatoes, 60-75 for romas).

Add to that, the reason I want to use the perforated row covers is cause it will increase the warmth, resulting in faster germination.

Also they will be grown in containers which means the temps of hte soil in the containers will be warmer in comparsion to the soil temp of soil in the ground.

So would this result in an earlier maturing date, and an earlier harvest date as a result (in comparison to growing them in the ground)

It sounds to me like this is an experiment that you really want to try. - So go ahead. We all have the need to see what rules we can get away with breaking.

Maturation dates on seed packages are very misleading and rarely correct. Often they are based on when you transplant out a 4-6 week old seedling, not when you sow the seed. You wlll probably do fine with tomatoes, possibly with eggplants, they will just be later than average. Id be surprised if you can get peppers to fruit before frost, unless they are hot peppers or a smaller sweet pepper of some sort. If it is really important to you that you be harvesting a lot of vegetables, then buying a few starter plants as well makes sense.