Pseudo randomization in MATLAB with minimum intervals between stimulus categories

For an experiment I need to pseudo randomize a vector of stimulus categories, 80% of which are category A, 10% B, and 10% C. The B trials must be at least three spaces away from each other in the vector, and the C trials must have two A trials leading up to and two A trials coming after them.

At first I tried building a script that randomized a vector and sort of "popped" out the trials that were not where they should be, and put them in a space in the vector where there was a long series of A trials. I'm worried though that this is overcomplicated and will create an endless series of unforeseen errors that will need to be debugged, as well as it not being random enough.

After that I tried building a script which simply shuffles the vector until it reaches the criteria, which seems to require less code. However now that I have spent several hours on it, I am wondering if these criteria aren't too strict for this to make sense, meaning that it would take forever for the vector to shuffle before it actually met the criteria.

What do you think is the simplest way to handle this problem? Additionally, which would be the best shuffle function to use, since Shuffle in psychtoolbox seems to not be working correctly?