Unordered list element via templating
Interesting questions.


Is setting 'style' still considered bad practice when creating elements through templating?

Only if you cannot reasonably use css classes (which is your case)
Should I be setting the style using jQuery after I generate the HTML from the template?

Since you know the height and size prior to generating, you should make this part of the template


Also, this : 

&lt;ul id="FrontRack" style="
        background-image: url({%= data.get('racks').at(0).get('imageUrls')[0] %});
        height:{%= data.get('racks').at(0).get('pixelHeight') %}px;
        width:{%= data.get('racks').at(0).get('pixelWidth') %}px;
"&gt;
    &lt;li&gt;Hello World&lt;/li&gt;
&lt;/ul&gt;


Only accesses data under data.get('racks').at(0), so that is what you should provide to the template ( as say, data ), then your template becomes

&lt;ul id="FrontRack" style="
        background-image: url({%= data.get('imageUrls')[0] %});
        height:{%= data.get('pixelHeight') %}px;
        width:{%=  data.get('pixelWidth') %}px; "&gt;
    &lt;li&gt;Hello World&lt;/li&gt;
&lt;/ul&gt;