Purely my own thoughts on what is appropriate:
For monthly production of a military unit (BA, 'Mech, SF, CV) I'd peg it at roughly 1 star per month of production. For component or ammunition production maybe a couple of points per month. Against opponents your clan abhors, add another star in for every 3 months (or portion thereof) of production), friendly opponents, decrease the defenders by half.
For ownership of a facility, I'd go with a cluster per manufacturing line (likely maxing out at roughly a galaxy) for units. Component or ammunition facilities drop that down to a trinary or a pair of binaries, depending on importance.
A continent doesn't seem like something a clan will typically trial for (yes, I know Alaric does it, but that was much more of a political move than typical clan trialing), more likely it will be for particular enclaves. A small enclave would be defended by a star or nova, a medium sized one defended by a trinary or pair of binaries, a large enclave around a cluster, and a pair of clusters for particularly large or important enclaves.
Planets, in the homeworlds, galaxy vs. galaxy would be the norm with capitals being defended by at least a pair of galaxies. In the Inner Sphere, it depends more on the expected defenders. Against a militia, no more than a trinary, against a regiment 1-2 clusters, against an RCT 2-3 clusters. If the clan wants to annihilate the regiment or RCT then they might up it to a galaxy (we see the Bears doing this during the Jihad against WoB forces).
Genetic legacies are usually going to be trialed for (and against) by particular warriors of said legacy. So I doubt that they would be using anything more than a trinary for your average bloodhouse, particularly prestigious bloodhouses are likely to have a correspondingly higher number of descendants, so I could see up to a cluster defending their legacies. As for the use a legacy without the ability for their spawn to acquire the house bloodname (patrilineal line, iirc), decrease the defending forces to a star and trinary, respectively.