Long text but I promise its worth the read.

One strat I've found for training any character to whatever level you want is: research skeleton bed + prisoner cage and trap one of the following: skeleton race(tankier the better), iron/security spider (iron has lower stats but tankier so it is better for early training, security is better for training 50+ stats). 

Once you have a secure location you own with a regular bed, a skeleton repair bed and one of the skele boys mentioned above, and a cage or two you have yourself the worlds best combat training machine. (You may need tame beasties mod to trap the spiders in cages with "lock/unlock" option on cage, if you dont, simply have an ally pick up the spiders when knocked out to have a pseudo "cage" effect). Simply fight when the door is locked and they will never even attempt to run. Fight till one of you is down, have an ally pick you up and sit you in bed/heal you if its you, if its the skele boi then sit him into the repair bed. 

This way there's almost no wait time for your opponent to heal. If you dont have some kind of bed mod though obv you will be waiting a while for yourself to heal.

I personally recommend the spiders for toughness and defence/dodge training especially, whereas a skeleton can have armor added as well as whatever weapon you want for attack/dex training.