In general*, it is a bad idea. Even a two column table will look fine when centered on the page and with 1+ inches of white space between the columns. It is the norm*, for thesis style to have lots of white space margins, double spacing, non-wrapped tables and figures, single-column, etc.
They are not usually set with anything approximating the layout in a journal. (Even for journals, they often have an easier time type-setting articles that have simple "white paper" style formatting with figures/tables at the end, etc. versus attempts to make the thing look like an article ahead of time.) In addition, I think you will find it easier to maintain the formatting of the document over time (as you write it), if you don't do some complicated setting of two tables side by side.
I did my thesis with the tables/figures at the end of each chapter and used endnotes versus footnotes for the citations (like a white paper or journal submission...and several chapters were sent to journals almost as is). This was received fine in terms of the review committee and the "ruler lady" (grad school format czar who checked white space and such). In general, I advise to write clearly and simply and truthfully and with good content. Elaborate typography is not desirable and can make your life a hassle as you work with a large document over time (distracting you from the core content).
*Of course follow your local thesis style guide. I am giving you general advice.