Yeah just cut that part off, it'll be fine. I like how the plants are enclosing that space so well, they should take up the whole room while flowering even if you half to cull out half of them after sexing.
I can't tell if they are male or female yet. You need to get a really good clear close up of the nodes near the middle of the plant. that whole region is usually where I see my first preflowers.
There seems to be a lot of 5x5 tents in my area for sail on craigslist, for cheap, I never payed any attention because I run horizontal 600w, but it seems perfect for 600w vertical. I think I might give it a try. I already bought a 4x4 tent to try scroging, and I am about to buy a 3x3 tent for moms and larger vegging plants... but I think I will put the scrog in the 3x3, because I only use 600w for flower, and I will veg and put moms and T5 in 4x4, and then vertical in the 5x5. Basically see if I can make more yield in the 3x3 with a compact "stealth" style like SCROG or a 5x5 ballsy vertical grow, which isn't so compact on this scale.
LST looks good though, if you keep the plants nice and healthy you are guaranteed a dank as fuck harvest.
You have maybe a day or two at the most to clone those things without the clones revegging on you. You are probably going to end up with some buds that you are going to fall in love with, but never be able to smoke again unless you take a clone. Or it could just be an amazingly easy plant to deal with and high yielding. Either way, you better do it before it's too late. In my opinion, revegged clones are garbage.
My best tip for flowering is keep your RH around 40-45% and you probably shouldn't do anymore LST now that they have started to flower, at least not after the first week or two. Flowering is all about timing, you need to know what to add and when, and how much. For most 8-9 week flowering strains they eat the most between weeks 3-5, so at the start of week 6 we should start decreasing nutrients, if you aren't already flushing. I really don't feel a 2 week flush is necessary in DWC. 9 days is the longest I have ever gone in hydroponics, and that is pretty long. Some people do two weeks, but I don't know, it depends on you plant mostly, I suppose.
Also, now that they are in 12/12, all the shoots and stalks will stiffen up pretty quick, so don't fuck around with them too much, or you could snap a plant, I did that once to a SFV that was 2 or 3 weeks deep.