I agree with you, but it would be nice to get all conservatives to agree to vote on particular good republican candidates OR on the same 3rd party alternative. It's the latter that would be of huge concern to the progressives.
The Constitution Party is a joke. It didn't even try the last election.
The Libertarians try, but they need their platform tweaked to be pro-life, pro-defense, and within reason pro-law and order.
The Libertarians generally argue that if governments kept their nose out of places they didn't belong, their stances on many issues wouldn't matter. If, for example, parents could without government involvement readily send their children to whatever schools best reflected their values, the question of what values should be taught in school would be removed from the political arena. Philosophically, the argument is generally reasonable, though in some cases I don't think it holds (for example, libertarians claim that unwanted immigration wouldn't be a problem were it not for government handout programs which shouldn't exist in the first place; I would posit that while such programs may cause immigration to be a bigger problem than it would be otherwise, they are not the *only* problem, and the need for border security would exist even without them).
Unfortunately, many Libertarians seem to think that if the behavior forbidden by law X wouldn't be a problem were it not for Y, and if Y should be eliminated, then the fact that Y should be eliminated means X should be considered unnecessary, even while Y--and its associated problems--continue to exist. While I used to consider myself Libertarian, the way in which they prioritize their efforts seems inconsistent with what they claim to be their most important stated goals.
Still, your reference to "law and order" is interesting. I would posit that true conservatives should be pro-law-and-order, but should recognize that policies which would undermine the Constitution--even when put forth by so-called "law-and-order" politicians--promote neither law nor order. Things like asset forfeiture might have been intended to improve police effectiveness in the fight against crime, but encourage police to prioritize their resources according to the value of assets that could be seized from a suspect, rather than the extent to which the suspect endangers the public. That's not to suggest that cops simply ignore criminals who don't have any assets that are worth seizing, but policies that create incentives for government officials to do the wrong thing are dangerous. Even if they don't immediately cause officials to start doing the wrong thing, they'll often start officials down a slippery slope which in many cases could and should have been avoided entirely.