What can be done, what should be done, and what is done can be three VERY different things…
CAN BE DONE:
I can’t find the article (I had it saved in a links file that was deleted!

) but I have read that deacons as clergy in fact do have the right to wear clerics (black shirt & collar) under canon law and local bishops may not abbrogate that…
I also am pretty confident that a cassock and surplice with stole would be the appropriate choir dress for a deacon (married or celibate) who is “in choir”…
SHOULD BE DONE:
I am familiar with one diocese that “allows” deacons to wear non-black clerical shirts (they usually wear grey) which is probably a good comprimise. The designation of a distinctive clerical dress code for deacons and possibly a distinctive style of cassock (in the same way seminaries in Rome have “house cassocks” for different colleges) would probably be a good idea. It would underscore that deacons ARE clergy, and be befitting of this clerical dignity.
WHAT IS DONE:
There has however been a trend to have deacons avoid clerics and cassocks altogether in most places. I am pretty sure that is not defensible by canon law to “forbid clerics/cassocks” but the intent of it is to avoid “clericalism”. (Frankly, I understand what they are trying to avoid, having been to seminary, I have dealt with the subset that would sleep in cassocks and birettas if they were allowed, but…)
Unfortunately this seems to have mostly backfired and had the net effect of giving a lot of people the impression that deacons are laity (I have heard the term
lay deacon!)… A lot of people don’t understand that the deacon is in Holy Orders and not just a “super altar boy”.
Most places I have experience with have told deacons to not wear clerics and when it comes to liturgy or choir dress an alb and stole is standard. (Actually, where I grew up, I had NEVER seen a deacon in a dalmatic even when serving at Mass…)
Frankly, a penchant for clerical dress when no one else shares it only makes you stick out like a super-sore thumb. Even if you are in the right, being “that guy” can lead to an undue amount of needless stress. Picking our battles is important!
I went to seminary and I can tell you that guys who seemed to like it too much or had gone so far as to have custom cassocks tailor made were pretty universally castigated and to their face and behind their backs they would be called names from “gay” to “Pre-V-2-Crew” to still other more tasteless invectives. Some of the formators would be concerned they were “overly clerical” and in some (not all) cases the formators MAY have been unto something. (In other cases it just served as a convienant excuse to intimidate guys who were too vocally orthodox…)
But after that overly long answer, a better answer still is:
Ask your bishop.