Yes my dr told me all that they have at Kaiser is alcohol based But he is willing to prescripe 25mg in addition to my protocol.
Whether you use cream or gel I would suggest that you appropriately reduce the amount of the injectable T. If you add the transdermal to your current dose you would make 2 changes: the mode of delivery (to deliberately raise DHT) and the total amount of T administered. Therefor you wouldn't know if it was the increased DHT or the higher TT that effected any changes.
In any event Your comment that you don't want to raise your TT any higher is good enough reason to adjust your current dose.
It should be possible to make a calculation of what the new injectable dose would be from the pharmacokinetics of the transdermal and the current T dosage. Although the reduction of TT level is non-linear to the reduction in dose it should be accurate enough.
At the end of the day there's no need to get too tied up in the math: if you use a moderate amount of a transdermal then your suggested reduction from 100mg to 80mg per week isn't going to be far off and once you're into the revised protocol you can make changes to the amounts of either/both of the delivery modalities depending on results.
I hope that you find a workable solution and that you will report the outcomes.