I must admit when i took ferrets in i had more problems with homing jills than hobs, basically they were as you have described, not just in the summer either, i had rows of cages full of solo jills who i had to seperate due to constant fighting, but i did find that having a very docile vasectomised hob helped, i basically left him in a run full off jills all year & he served each one who needed bringing out of season, i also managed to house a couple of castrated hobs in there as well, i had a group of around 15 ferrets all living happily together, the jills rarely came back into season af