No there is not a way to add any more filters as long as you are still using their opaque feathers and that means that you could very well end up getting long layovers and many connections. A few tips to getting a good deal:

1st, unless you really just want the cheapest possible way to getting from one place to another without any regard to any possible problems that will be involved, DO NOT use those opaque deals. 

2nd, Clear your browser history and internet cookies. These sites use your internet cookies (if you don't know what those are, it is simply your past search history that sites can use to there or your advantage. You can look up how to clear them.) to see how often you have looked up a specific flight path and if it sees you have done it a lot, it will actually start bumping up the price as the date gets closer. Also search it in Incognito (for Chrome) setting so that the history is wiped off right away.

3rd, use Kayak to search. They do not sell the tickets. They just give you the best prices from everyone else and they give you a lot more filters.

4th, notice most 3rd party sellers have a fee of their own on top of the rate. For example. If the hotel is selling rooms at $99 ($111.27 after tax) the 3rd party sellers will advertise it for $79 plus tax and in small letters plus a $20 fee thus making it after all is said and done $111.27. So you really are not getting a deal at all. 

Lastly, after looking up the best option, call the airline or hotel directly and make certain they are not able to give you a better price. Unless it is already their normal rate, they will not match the rate, but often it will already be their normal rate or they could get you a better rate.

I hope this helped.