Welcome To Bike Forums, Evahrt!

I say, keep the MTB as a spare, just in case of an emergency. However, traveling the distance that you're traveling, I think that you should either get a performance hybrid with barends, or a genuine road bike. If you can't afford a new one at this time, then just monitor your local Craigslist, to see what's available. Meanwhile, get some slicks for your MTB and roll on!

Join a nearby bicycle co-op, so that the leadership or bicycle mechanics there, can assist you with locating a chromoly steel bicycle frame. They will also be available to provide you information concerning any repairs, ugrades, or adjustments, once you've found a bicycle frame.

Locating a bicycle on your local Craigslist:

Make certain that you have someone with you who "knows bikes". That will be your "expert". Have your "expert" inspect the CL bike, both before and after your twenty minute test ride. Your expert should be able to advise you about the overall condition of the bike and your approximate fit upon the bike's frame. If you suspect that the bike is little too large, it most probably is, so don't buy it!

Buying New:

Always buy new, if you can afford it and know exactly what you're looking for. The following would be my recommendations:

1) The Jamis Satellite Comp ~ $1000
www.jamisbikes.com/usa/thebikes/road/satellite/12_satellitecomp.html

2) The Jamis Satellite Sport ~ $700
www.jamisbikes.com/usa/thebikes/road/satellite/12_satellitesport_gy.html

3) The Motobecane Fantom Cross Outlaw ~ $1000
www.bikesdirect.com/products/motobecane/outlaw.htm
(Get the brushed silver model. It's gorgeous!)

4) The Jamis Coda Comp ~ $775
www.jamisbikes.com/usa/thebikes/street/coda/12_codacomp_bk.html

5) The Jamis Coda Sport ~ $560
www.jamisbikes.com/usa/thebikes/street/coda/12_codasport_bk.html

Good Luck!

PS.

Always stick with steel when buying used, unless you know about the frame's history...