Touring - Chainring change for Touring

I would like to do a tour (Pittsburg to Wash. DC trail) late this summer with my son. I have a KHS Hybrid (see link) that has a 28/38/48 crankset and a 11-32 cog. My question is, can I replace the 28T with a 24T or 22T and not have to make any other changes? I plan to have my LBS do the work but should I purchase the needed parts? I plan to pull a Nashbar trailer and install front panniers. I hope to stay under 55 lbs of gear. Any advice you might give will be greatly appreciated.
http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=2006&Brand=KHS&Model=Eastwood+C20&Type=bike

I would like to do a tour (Pittsburg to Wash. DC trail) late this summer with my son. I have a KHS Hybrid (see link) that has a 28/38/48 crankset and a 11-32 cog. My question is, can I replace the 28T with a 24T or 22T and not have to make any other changes? I plan to have my LBS do the work but should I purchase the needed parts? I plan to pull a Nashbar trailer and install front panniers. I hope to stay under 55 lbs of gear. Any advice you might give will be greatly appreciated.
http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=2006&Brand=KHS&Model=Eastwood+C20&Type=bike

This (http://www.sheldonbrown.com/gloss_bo-z.html#bcd) page gives specifics.

If you have a crank puller, changing chainwheels is an easy job for you to do at home. That said, a mechanic just told me that I didn't get the "ramps" lined up when I swapped out a chainring on my bike recently. No big deal, but shifting should be a bit better when I fix this.

Yes the small chain ring should work fine. The one danger (and its really not a danger) is that your rear deraileur will not be able to take up chain slack if you ever tried to use the small chain ring with the smaller cogs in the rear (this something you should try to avoid anyway because it involves a cross positioning of your chain. Try that small small combination to see if it causes problems if you accidentally arrive at it, and if its a problem you can avoid that combination or take some links from the chain (if you can do so without jeopardizing the big big combination (also to be avoided). I hope this helps. tom

Thanks for the reply. I'll have to wait a bit. Bike is going in to the shop for a cracked frame. LBS has contacted KHS and the rep will be there tomorrow to evaluate. Bike was purchased new Oct. 2007. I have a little under 2000 miles on it. The crack is in the middle of the tube not at a weld point. Frame is aluminum. Wish me luck!!