Tribulus during a cycle is worthless. The means by which tribulus stimulates test production won't work at all while on juice. Basically, when you're on long cycles, it isn't about maintaining natural test while on, but instead, regaining natural test production as quickly as possible after coming off.
Some people believe more in Clomid, some like Nolva, some choose an anti-aromatase. Whichever you choose, as far as from the perspective of shortening recovery time post cycle, the reasoning is that by inhibiting the action/aromatization of/into estrogen, you will be able to recover more quickly, basically because you weren't shut down so hard. In other words, if you can keep estrogen action, or aromitization to a minimum the hpta won't be AS supressed as it would be if no anti-aromatase, or anti-estrogen were used.
Personally, I use 20 mg/day nolva while on and 10 mg/day while off. In MY opinion, nolvadex is superior to anti-aromatase drugs because even if the exogenous hormones you're taking aren't aromatized, the anti-aromatases won't do a thing for administered exogenous estrogen. Estrogen is in more foods and beverages than you can imagine. Taking an anti-aromatase won't do any good against the estro you consume. Nolvadex, however, will block the estro receptors so the results are superior.
Of course some people will just have a higher amount of the aromatase enzyme than others. So for these people, the use of an anti-aromatase is great while on cycle, along with some nolva.
I talk too much.