MEGA 2560 modify bootloader baud for XBEE

I'm hoping someone can give me some guidance on an issue I've been fighting for days. I have a MEGA 2560 R3 that I need to be able to program remotely. For comm hardware I have a couple XBEE's (Series 1). I have gone through several "HOW-TO's" on the web, and have the XBEES's talking well and am able to send data back and forth between my console on the PC and the MEGA. I also have the I/O on the XBEE's passing the RTS to the MEGA to perform a reset.

The problem is, I can't get a sketch to upload properly. I believe it's due to the high baud rate of the MEGA's bootloader (115200). At least I think it's 115200. I've also tried 57600...

What is the default uploader baud rate on the 2560? I have conflicting information.

What I would like to do is modify a bootloader to use 19200 as it's upload baud (more stable over a longer range radio link). I'm pretty sure it can be done, but I have no idea how to do it.

Can anybody offer any advice or example bootloader code?

Should I start with the stock bootloader code, or is there a modded bootloader out there that would be better or already does this?

What bootloader does the 2560 use by default?

How can I modify my boards.txt file to be compatible with both this new bootloader and the stock bootloader?