Newbie needs advice on cold nights in Texas!

Hi! I'm a new SFG as of early March. Man, this crazy Texas weather this spring. Its 80 degrees for a week and then dips into the 40's! I'm not sure I picked the right time to start. As you can see by my avatar, I have constructed a 4x8 bed topped with a "covered wagon" that is coevered in bird netting.

Since planting my tomatoes 3/27 and peppers 4/20, I have been covering my tomato and pepper plants with buckets overnight when the temps are dipping below 48 degrees.

Last night, with a forecast of 38, not only did I cover the tomato and peppers with buckets, but then I draped the whole bed in plastic to protect the carrots, radishes, chard and lettuces. I waited until 11AM this morning when the temp actually reached 48, even thought the sun was out and I could see condensation on the plastic. All looks good EXCEPT for two peppers and 1 tomato. Their a bit droopy, as if they got too hot. They are still plenty moist.

So, my question (finally!!) - is it really necessary to be covering the plants when the nights are staying in the upper 40's, perhaps dipping to low 40's just at dawn for an hour or two? The forecast tonight calls for high 40's until 3 am then a drop to 43ish for a couple of hours, but it will be back up to 50 by 8AM. Am I doing more damage by not letting them get used to the variations in temperature??

Sorry to be so long winded. Any advice for a novice vegetable gardener is greatly appreciated!!

The other crops will be fine without any protection--up north here mine regularly experience low/mid 30s without issues. I'd continue the bucket idea with peppers and tomatoes with lows reaching the low 40s--the ground should radiate enough heat to keep them warm under one of those buckets--do you have a thermometer under one of the buckets to see how cool it gets under one?

Thanks for the quick advice! No, no thermometer. But when I took the buckets off today all was toasty. The buckets AND the soil. I think the layer of 4mil plastic over the whole bed held in a bit too much heat with the sun shining. I probably should have uncovered earlier, but I was worried about the temp not rising. I'll skip the plastic tonight and continue the bucket brigade! Thanks for the advice.