To be honest, I hate T3 and won't touch it. That will eat at your muscles. Clen, on the other hand, has been shown in a number of studies to be anticatabolic and prevent muscle tissue loss (OhNoYo will fight me on this I'm sure
).
Saying that you will lose muscle even on high dose AAS is ludicrous. You don't need to cycle any AAS while taking clenbuterol if you don't want to.
Next, you can cycle clen for a month straight or more if you add in Ketotifen Fumarate (Keto). Clenbuterol usage results in severe down regulation of beta receptors. Therefore, after a period of time it becomes ineffective (non-thermogenic). Ketotifen helps up regulate the receptors so they remain active for the Clenbuterol to work it's magic.
Start with 20 mcg a day, increase the dose by 20mcg every 2 days until you reach 120 mcg. Stay at that dose through the end of your cycle. As for the Keto, start with 0.5 mg on day 1 and work your way up to 2 mg by the end of week 2. Do not move to the next dosing level until you are comfortable with the level you are at...this is very important (for Clen). Take your full daily dose of Clen all at once in the morning and your full daily dose of Keto all at once about 30 minutes before bed.
With Keto, you will not need benadryl, but you will need to take about 5 g of Taurine per day to replace what the Clen has depleted from your liver.
Cheers