Rumbaed and sambaed are both accepted but my dictionary also lists rumba'd and samba'd. I don't understand the latter - why elide the e? Apostrophes in that situation look wrong to me.
You were right! ;)
I was right! ;)
We were both right! ;)
I understand why apostrophes feels wrong to you.
To me, it feels like a misspelt word whenever I see an 'a' followed by an 'e' in any word, except for the British spelling of old words like 'archaeologist'.
The dictionary suggests you may choose your poison; neither is fatal.
As I understand it ...
Apostrophes before 'd' or 'ing' only exist for extremely unusual situations.
* One is when something that doesn't look like an ordinary word needs to be used as a verb. OK'd and OK'ing were, until now, the only examples I knew of that were listed in a dictionary. I am sure it is the correct way to conjugate the verb, Chanel No 5.
* Another would be to prevent an ambiguous word, for example if you want to use one word as a verb, but another verb already exists with the same spelling, except for an 'e' on the end.
I see the allowance of rumba'd as analogous to the option writers have when adding prefixes. For example, dictionaries say preexist is a valid word, but writers are entitled to use pre-exist if they feel it will aide in clarity. SB has said he sometimes does that with re-read. Dictionaries do not list that as an option, but I have no problem with writers doing that.
So, going back to the example you came up with - which I imagine you thought was showing I was wrong by finding a ridiculous example - I have absolutely no (theoretical) problem with you pressing Coca Cola into service as a verb, and when you want to create the past tense I believe the correct forms are either: coca-colaed, or coca-cola'd.
Aren't we always arguing here that we should never allow to restrict our creativity needlessly. Go ahead, do whatever you want, but if you want readers to understand a verb that's really strange, this is how to do it!