You absolutely could, but it WOULD be a good idea to keep something on-hand such as HCG.
Here's what I think- you're using transdermal prohormones, you're NOT using injectable, active steroids. The difference is that a conversion process occurs, which after a peroid of 8 weeks, I imagine would begin deminishing. Compare this to the user who's using injectable steroids, and there's absolutely no down-regulation or conversion changes. The active steroid (since there's no conversion) is the same on day 90 as it was on day 1- the amount you're injecting. In your case, the conversion levels are bound to change during the same length cycle.
Since you're tossing around the idea of using this for 12 weeks, I assume you've got a small treasure stashed away. Why not just do two, 6-week cycles? If what I'm saying has any merit to it what so ever (that conversion will down-regulate to help maintain homeiostasis) then would you gain MORE using the transdermal for 12 weeks straight, at the cost of a difficult PCT and a greater percentage of muscle loss, or for two, 6-week cycles with a simple PCT and most, if not all gains retained? Personally, I hate PCT. It's a shitty time for everyone. And although I only cycle 2-3 times a year (at the most, and all relitively mild) I still wouldn't want to be shut down for long peroids of time if I had intentions of doing another cycle in the near future.