you should be able to do some breeding without using any more space than what you already have.
step 1: take colidal silver and spray a small area on a plant you want to hermie. you can do this to one of your girls that are already in flower and just do it @ week 6 or so of flower so even if the pollen does escape the plants wont have time to develop any seeds, but if your carefull you shouldnt have any pollen contamination. just keep your spray sites small.
step 2: wait for nanners to pop and develop and collect them just before they open up.
step 3: use pollen from collected naners to brush on a small budsite to make some seeds. use a tag or something on the site so you knw where you bushed and simply remove that site before harvest and set aside to dry out
step 4: collect seeds and plant.
this is at least what i make of it. i wont breed using males due to the same problem you have, space restrictions. but to produce feminized seeds using collidal silver as a stressor to make a plant hermie wont pass on any additional hermie traits because the plant dosent have them, you forced it to hermie.
anyways like i said thats what i want to try doinf. not sure if its the right way or not but only one way to find out right?