HERMS can definitely help with your mash temps staying more consistent. What are you presently using for a mash ton? While you design and perfect a HERMS sytem which can take a bit of time and money, here are some suggestions to help maintain your current temps assuming you are using a cooler.
Cut a piece of styrofoam board to the internal diameter of your mash ton. Poke two small holes in the top and run a plastic tie wrap through them to use as a handle. Place this over the top of the grain bed after you have stirred setting it down on top of the grain, then put your lid on. This greatly reduces loss to the dead head space and through the lid. In a cooler a big source of heat loss is through the lid that is ofter under insulated, or not insulated at all.
Pre-heat your mash ton. You can do this by putting in heated water a few degres higher than your projected mash in temp about 5 minutes before you put the grain in, or I sometimes just use hot tap water to at least get it up to 130 or so then drain the tap water before putting my strike water in.
Wrap a small towel around the drain valve. The valve is an excellent conductor of temperature and acts like a heat sink drawing heat out of your ton and radiating it to the outside air. A small towel will help insulate it.
Do not set the ton on a cold surface. Wrap a towel or blanket around the mash ton, paying attention to the top and bottom.
Good luck with your HERMS plans.