This is a question that probably should be submitted to Dreamhost support for an authoritative answer - most of us active on this forum are customers just like yourself, and while many of us have a lot of experience with DH, we cannot speak for them.
That said, the chances of getting an account canceled for spamming in the situation you describe are pretty good. The process used for evaluating a spam complaint at DH has been explained to me, and it is my understanding that when a complaint is received it is investigated.
While the contents of the reported spam email are reviewed, the fact that it may contain a "optout" or "remove" link does nothing to decrease the "spamminess" of the mail.
Dreamhost's policy is very strict, and they are very serious about maintaining a "spamfree zone" when it comes to their accounts.
Note that Dreamhost policy actually requires more than the "url from where the person signed up", it also requires a "confirmed opt-in" status (they have to sign up first, and then confirm that they signed up with a second action). This must be documented with the ip address and the date time of the original opt-in and the confirmation. One of the things that will be evaluated when a "spam" report is investigated is whether or not these rules were followed.
Your cards will not accomplish that, any more than, for instance, maintaining "membership applications" where people have "agreed" to receive email marketing, and signed them.
There are actually several "good" reasons for this, though they may not be readily apparent. You might find reviewing this forum thread on "how not to be a spammer" useful in understanding part of what is involved.
To me, the bottom line is to use the DH announce-list management tools to send marketing email, as they provide all the "backup" Dreamhost requires to handle a "spam complaint". There are even instruction in the DH wiki on how to use an existing list with reasonable safety and policy compliance with these tools (basically, you send a "one time" mail to those whose gave you a card, or signed up in some "offline" manner, and they then confirm back that they want to continue to receive the mail - if they do not, you dump them from the list).