You definitely don’t want any seeds it will negatively effect the oil production. My lightly seeded crop only yielded about 5% return on rosin or ice water hash.
I think you are making too much of this. Ditch the ScrOG unless running feminized or clones. Plant twice as many as you need, veg them until the space is full, flip to flower, once males show, kill them. The girls will get more room to stretch. K.I.S.S.
or…
Plant twice as many as you need, veg until alternating nodes, take cuts (make sure to clearly label them) and put them in a cup of water under 12/12, maybe under a bathroom sink or somewhere like that. In a week or two, they should start to show sex.
I haven’t tried this one, but…
I heard about this from SkunkmanSam on Hash Church this week. It was in relation to greenhouses, but still applies here.
Plant twice as many as you need, veg until alternating nodes, give them 2 full days of complete darkness. Then return to you normal veg cycle. They should show sex two weeks later and you can cull the males.
or…
If you have money to throw at the problem (I know you don’t and mentioned that already), Phylos Biosciences sells a gender kit and can tell you the sex from seedlings as young as 7 days. It’s about $80 for four plants.