I agree that it should have plenty of power. You should not be able to overheat it unless it is constantly noticibly bogging down. I have more power, but I run a 6 footer and the temp never rises above normal except when I am mowing something with a lot of seeds that keep clogging up the screen. My tractor will bog down in the thick stuff long before overheating is an issue. You may have less power than the bigger brothers in that family but you also probably have the same radiator so there is less of a heat load on it.
As mentioned already, flush the system... your cooling system is not running at peak efficiency. Only other thing to check is maybe air filters and possibly exhaust blockage.