Speculative bubbles would not be a problem in the blueprint I provided above. Bubbles occur when a product or asset is traded for much higher prices than they're actually worth over a substantial period of time. In an actual free market that wouldn't happen. Booms are caused by artificial lowering of interest rates by central banking systems like the Federal Reserve; entrepreneurs think that with interest set to those lower rates that they will be able to make enough money from an investment to cover the immediate costs of investing. They end up taking more risks specifically because the Federal Reserve encourages it with its artificial interest rate adjustments, and when these risks predictably blow up, the bubble bursts. Without the Federal Reserve artificially adjusting interest rates, entrepreneurs would not be taking these risks.
As for how they treat workers, there's no reason why a small government couldn't enforce fair labor laws. We'd have to discuss exactly what that entails, but again, small government =/= letting big business run everything. In fact, since the comparison is to big government, it's easy to see why small government is superior. Big government of the sort we see here has been in bed with big business precisely because it intervenes in the economy. Big government is a player in the economy with its own ability to influence events and outcomes. Big business funds politicians' campaigns, politicians use big government's influence on the economy to the favor of those big businesses who financed their run for office. Small government acts as a referee instead. By staying out of the economy and staying dedicated to staying out of the economy, it keeps itself free from corporate corruption and can fairly enforce labor laws without worrying about its entrenched interests in big business.
I cannot stress enough that small government is not rampant corporatism. What you've historically seen Republicans parroting around is right-wing big government, NOT small government. Big government gets involved in the economy; whether in the interests of business (right-wing) or to combat business (left-wing), it invariably gets involved. Small government does not. Small government is an enforcer, not a player.
The environment is a tricky issue. Let's look at one important thing I've already proposed, first -- the end of corporate welfare. That means no more sweetheart deals for big oil. Oil companies get substantially more government support than clean energy research and development firms; cutting those subsidies advantages clean energy, and does so in a way that also fulfills the libertarian idea of less government intervention in the market. It also removes subsidies for alternative energy that has proven inefficient and is effectively only propped up by government subsidies. For example, ethanol is not economically feasible. Ending corn subsidies for the purpose of ethanol production frees up government money to be used elsewhere and ends the propping up of an unfeasible, not viable energy source. This then allows investors who are still pumping money into the failed-but-still-living government-backed ethanol field to invest in something that might actually work (wind, solar, whatever).
Another environmental issue that can be handled easily by a small government is pollution. There's an easy fix: start treating pollution as a property rights issue, not an environmental issue. Then it's a slam dunk. If a company dumps its shit onto a community, the community takes legal action. It's just like if I were to go carry my trash over to your yard and just dump it there instead of using the trash service in place. There's no question that you would effortlessly win a court case against me for that. Why shouldn't it be the same on a larger scale? The reason we don't see pollution handled this way now is because historically it hasn't been properly enforced as a property rights issue. Start looking at it from that perspective and the remedy is a lot clearer (no pun intended). Hell, there goes a big part of the concern with global warming. If pollution of the air with greenhouse gases starts to be looked at as trashing the local air space (which is conceivably communal property maintained by the governing body that controls the land over which that air resides) instead of simply warming the Earth, then it can be easily handled in courts and keep companies from rampantly contributing to the buildup of greenhouse gases. I don't have a right to desecrate the parade grounds in front of the state Capitol, why should I have the right to desecrate the air around it?
If I'm missing something major then by all means let me know, but libertarianism and the dignity of workers, the safety and maintenance of the environment, and the avoidance of economic bubbles are not only not mutually exclusive -- libertarianism can *promote* these things with sound policy that does not contradict its fundamental principles.