You are killing your batteries! If they are getting anything more than slightly warm at the end of the charging cycle, you are charging them at too fast a rate with too high a charging current. 200mA is the fastest you should ever charge AA NiMH batteries. While your method of charging batteries may seem to be giving you more charge life, in the long run, your batteries are going to die sooner than they would have otherwise. Besides, all that cool down and recharge again rigmarole is more work than the little gain you get will justify. It would be much easier to just carry some spare batteries and change them out when they run down.
If you don't have one already, get a good "smart" charger, such as the La Crosse BC-700. A smart charger does a better job of regulating charging current and will taper off the charge toward the cycle to avoid overheating, preventing damage to the battery (as you seem to already be aware of, heat is deadly to batteries). Even though the BC-700 has charge rates higher than the default 200mA, you should use them only if you get a "stuck" battery, one that doesn't want to reach full charge. The handful of "stuck" batteries I've run into responded to 500mA, then could be recharged after that at the safer default 200mA.
If you aren't using low self discharge NiMH batteries, I highly recommend Sanyo Eneloops. I have some that are several years old and are still going strong. Unlike regular NiMHs, which can drain themselves in as little as a month, LSD NiMHs, such as the Eneloops, will hold a large percentage of their charge for as much as a year or more. Since a rechargeable battery's life is measured in number of discharge/recharge cycles, the LSDs will last far longer than conventional NiMHs since they will not have to be recharged as often. I have Eneloops that are several years old and still going strong; out of over a hundred AAs and AAAs, I have yet to have one die on me.