If by blight, you mean the early blight, it affects most tomatoes to some degree before the season is over. I would suggest either plastic under the tomatoes or at least a good mulch. This is to keep water from splashing upwards on the leaves and beginning infection.

You should rotate your crops every year. I think even a little bit away from the regular site would help.

The best thing I have ever found for blight is mulching. I mulch my tomatoes with newspaper and grass clippings. I have less blight when I do a nice thick layer.

If I were you, I would grow tomatoes in pots as part of your crop rotation. If you use fresh potting soil each year you will never have to deal with blights at all, nor any of the insect pests that tend to nest in the soil, like flea beetles. Everything I read says you should not plant any of the tomato family (includes peppers, potatoes, and eggplants) in the same spot more frequently than every three years.

The trick to growing in pots is to use very large pots and to be very vigilant about watering and fertilizing. Seriously, I grow tomatoes in the ground and in pots, but at the end of the season, the potted ones are always the best looking and heaviest producers.

I think moving the tomatoes to pots for at least one season may have some merit. Maybe I'll plant half in pots and half in the soil. It may help me determine if soil is the problem.

don't waste your time trying to rotate crops, the simple home gardener has neither the room nor the time to rotate crops, use compost and/or fertilizer to raise the NPK
of your soil

the intent for crop rotation is to stop the disease and insect life cycles. moving tomatoes 10ft is not going to do this, other side of the 40 acre farm, yes.

crop rotation needs to be done over a life cycle of 3-4 years to break the disease and insect life cycle. BTW we don't rotate crops based on veggie, we rotate crops based on crop families. i.e. heavy feeders, light feeders, root crops, brassicas, legumes, etc...

Raising your tomatoes in pots, with new soil, is in effect the same as rotating, and likely a good idea. The soil that they grew in last year would probably benefit from a healthy dose of good compost and some unrelated crops that will help to remediate the soil, alliums and legumes would likely be a good choice. Remember that any peppers, eggplant, and potatoes may harbor the same blight spores, so be judicious with where you plant them next year as well.

I'm not sure where in Md you are, but remember that a good portion of the state grew tobacco as a cash crop for decades... I think diseases of the solanaceous plants may just be a fact of life here. Besides mulch and pots, you could look into solarization using clear plastic. I forget how high the temperature needs to be for how long, but you can pretty much sterilize your soil. This should rid the spot of any spore stages certain diseases. I think more may slowly re-enter the solarized area, but the point is to get the concentration of pathogens reduced to a point where the plant can hold its own. It is a bit drastic, though. Probably best followed up with some "clean" compost (sort of like yogurt after a round of antibioitcs)...

As for rotating, a third reason for crop rotation is that different plants use up nutrients and micronutrients at different rates. Personally, I don't find planting the various families in different rows each year to be too difficult, it pretty much happens naturally.