Hey Larry,
We just did the trip this weekend...the weather was great, 70's during the day and 40's at night
www.jeniko.com is the best deal in laptop mounts. They make on that uses the seat bolts and an extra arm for support, works well but it is $130
If it was me I would get this drill in model and adapt it since you have the welding ability or Bill can fab something for you
http://www.jeniko.com/cfl800-floor-m...c3e4ea68aaf0d3
Look around on their site.
The other option would be what I did on the Sportsmobile which is bring a couple of arm like supports out from the bottom of the dash. A little netbook isn't heavy and works well like that.
The globalsat 353 gps puck is the best unit around and is only $40.
I will add something about the laptop setup to my build thread soon...my setup was just a temp hack job to last the weekend but it would be a funny writeup.