While you can, we would suggest to not if you're interested in the fitness aspects of TRT (which most men are).

Enclomiphene is nice because it doesn't impact fertility the same way that Testosterone does. It functions much the same like HCG and Clomid where it encourages the body to create more of its own Testosterone. When taking it as a stand alone it preserves fertility more in the sense that it doesn't lower it like injectable Testosterone, but it's not nearly the same impact as HCG which more actively targets the area you're looking for (for fertility).

HCG/Clomid/Enclomiphene all improve your natural production, lets say by an imaginary value of by 20-30%. If you already have low Testosterone production (primary or secondary hypogonadism), which it sounds like you might at that 140mg treatment level, then remember that 20-30% increases on low values are not large numbers. The best use case for us of Enclomiphene would be someone who has relative hypogonadism (a higher base T production level) and they can get a larger benefit from the medication + they don't have to worry about suppression as much.

Why would we say don't take both if you're primary or secondary? Your natural production is going to be suppressed by the Testosterone either way, but Clomid/Enclomiphene also suppress IGF-1 in the body, the main benefit to muscle production/retention that is usually associated with TRT (and thus metabolism).

TL;DR: Probably not both, HCG might be better for you if my guesses about your type of hypogonadism are correct.