I was thinking this could also be done with clomid. Clomid supposedly has estrogen like effects on mood and libido. It's also a partial agonist in places like the liver, so there probably wouldn't be the serious issues that a person normally would have if they were to have no estrogen (low HDL etc.)
In my opinion, this is the best option for estrogen replacement while on cycle. Raloxifene might be even more estrogenic (agonist versus partial agonist) than clomid, so that could be an even better choice. The benefits of using a SERM instead of pure estrogen are that the dose would be much easier to control, the effects would be more predictable, and the effects would be skewed in a positive direction (more of an increase in libido, less water retention).
Another option is to use tren (or another nonaromatizing steroid) at a high dose, and add, for example, one synovex pellet per ten finaplix pellets. This would allow for precise estrogen control. Natural estrogen production would stop within a few weeks, and the trenbolone would be the main androgen. The problem with patches is that the dose varies from person to person, patch to patch, and even day to day. With intraamuscular estrogen, the exact dose would be known, and could be easily varied.
If you're using only nonaromatizing steroids, it might be a good idea to add a source of DHT. You won't be able to use testosterone, because some testosterone will always aromatize, even if you're using an AI. You could use pure DHT if you can find it. Masteron or proviron might be good replacements for DHT.
I think these are all good ideas. I know it's possible for some people to drive estrogen very low (too low)with letrozole, but still have issues with water retention and nipple sensitivity on certain steroids, like dbol. I don't know why that'd happen. Maybe the estrogen from dbol (methylestrogen?) is more effective in the breasts than the pituitary.
Anyway, I think estrogen replacement is a good idea. I think you should experimen, and report back. I don't know if I'd be willing to be the first person to try these ideas. They're not dangerous, but natural estrogen produciton might take a while to resume, or it might come back too high.
I think if someone is on TRT, a good protocol is 200mg masteron per week and 50mg clomid per day. I'm just making guesses with all of this, though.