Okay. Well I can tell you 6-10 in a 36 is not possible. Too crowded. I had my 5 German blue rams living with juvenile severums in a 55 gallon and it was tense for a bit. The sevs were slightly bigger and had their territory claimed on the bottom. Two of my rams paired up and pushed the sevs out of a corner spot to breed in. Well the sevs had to reduce their territories and there were a few minor disputes, but the other 3 rams had to stay in the middle and top layers, which stressed them a bit. I finally got a 55 just for my juvie sevs and now the rams have settled into the bottom of the tank. The breeding pair still has their corner and the other three get along well. I could only see adding maybe 1 more ram to the tank and even that might be too much as it could end with me having a second pair and two solo rams arguing over space. I would recommend at most 3 rams in a 30 gallon and maybe 4 in a 36.
The only problem with your desire of both sexes of the same species of cichlid in the same tank is that you have a very good chance of ending up with a breeding pair. The single sex method is the only way to ensure no breeding. Now you might get lucky with three rams and have a single male or female who refuse to mate with the others, but its a risk you would have to take if you want both sexes. Rams are not super hard to sex once they are almost full grown, but are nearly impossible to sex before maturity. My german blues are easy for me to sex because of their bright colors and black spots. I have heard Bolivians are a little more complicated due to less robust coloration than their blue cousins. Forget sexing gold rams. You will only know the sex of golds when you get a mated pair and see them reproducing.
Cory cats could be a possibility with rams depending of the attitude of the ram(s). South American cichlids are hit or miss as far as temperament goes. Mine are pretty mellow and most are from what I read. I have read a lot of success with the combo, so give it a try. Worse case scenario is you have to remove some cories or an angry ram.
As far as other dwarf cichlids, I can only throw my 2 cents in on kribensis. You could only keep 2 kribs in a 36 without issue because they get bigger than rams and need more territory. Kribs are super easy to sex at almost any size larger than 1.5-2" long. I have read keyholes are super mellow and get along great with almost anything they can't swallow. They get to 6", so you'd be able to keep 2 in the 36, but no more. They are about as hard to breed as rams as I understand, so with just 2 you'd not likely get a pair even if you did have a male and female.
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