Good idea. Though you probably have to rent it in advance. If you do this, go for a reputable dealer/renter. There are alot of nickel and dime tux rental places that don't care if the pants come in the wrong size and since they don't keep a lot of stock in the actual stores you might be up the creek with a pair of highwaters...
Check out
The Men's Wearhouse They have a tux rental site, you can at least see the various looks, options etc. They should also be able to help you with proper conversion sizes. Also, if you use the store rental shoes, buy yourself some cheapy but cushy inserts, i.e. Dr. Scholls, from a pharmacy. Those rental shoes can be really uncomfortable, esp. for long night of partying.
Have fun!