I don't brood indoors but some people do use the spare bathroom. I can't remember the details of how the lady I saw doing that had it set up. They will make a mess. I'd worry about the drain getting plugged, especially if you use bedding in the tub. By two weeks they could be flying all over. Hopefully someone that has done that will post some details and how it worked out. From what I saw I was not favorably impressed. More than your bathtub may be stained.My producers pride brooder heater is too large to place in the plastic box I planned on using. Only getting no more them 10 chicks . What should I do , should I hang it above the brooder.
What temperatures will you have in Mississippi when you are brooding the chicks? Do you have a garage or outbuilding that has electricity that you could use? Are there any adults in the coop and can you get electricity to it? Depending on what your coop looks like you may be able to brood in there.
A popular way to brood chicks is to use a garage or outbuilding. I'm not sure what that specific heat plate is rated for, some say don't use them in less than 50 Fahrenheit. Put cardboard down to protect your floor from being stained by the poop. If you can get a large appliance box use that, many appliance stores give them away. Or get two if one is not big enough and tape them together. Put bedding on the floor so you can clean it out. Put your heat plate in that like it is supposed to be used. When you are finished compost it or throw it away. I can't think of anything cheaper or simpler but I don't know what outbuildings you have to work with.