There have been several thrd's on bed covers, aux tanks and 5th wheels. This is what I did after reading several, thanks for the help.
I purchased a transfer flow 50 gal cross bed tank and installed it myself then added the truxedo soft top low profile bed cover so I could leave it on but rolled up while traveling with our 5th wheel (It can be removed by loosening 2 bolts if needed). This is my first try at pic's so Here is a description of the photos: Hole thru firewall location idea from a previous thr'd. Transfer Flow provides a 1 1/4 groment so many other wires could be put thru the hole with a larger I.d. groment. The tank is fed to the stock tank fill pipe with a double y fitting the line from the aux. tank pump is attached on the lower y and a vent is attached to the other(both lines come from the aux. tank pickup/fuel gage sending unit. There is a third hose from a tank vent with a roll-over valve on the top of the tank, just goes under truck to air. You have to drill 2 1 1/ 4 holes thru the bed for the 3 lines/vents and the electrical connections and 4 1/2 holes in the bed floor to attach the tank to the truck. The tank fit's under the bed rails with about 4 1/2 inches clearance except for the sending unit cover and fill neck which are 2 to 3 inches higher but still clear the low profile truxedo.
Hope this will be of some help to those thinking about added gas capacity and bed covers.

Nicely done!

Can you PM me on how you got the pics to insert? My insert image icon doesn't seem to work....
Thanks

What wiring was required to monitor the factory tank level and the connection to the TraxII?


Thanks!

Nice Job on the Photo's ! you sold me on the truxedo soft cover, I like the looks of it. Looks like it is easy to install and remove from the truck if you have to.
What type of Bed rails do have on the truck ? Did they get in the way of the
bed cover during the install?

I had taken the photos at a high resolution so I reduced them in photoshop to jpeg low resolution and changed the size to 320 x 240 then posted by picking the file name when in the attachment window, next time I will try adding text like most of the folks have done. I think, however you do it, low res. jpeg at around 320x...creats a quick loading photo, again first try, others have more experience on this.
This tank comes with a on dash monitor that displays the gallons in each tank then the total. The harness comes with directions to attach to existing wiring, on my truck I had to get into the factory loom along side the frame, cut the purple wire(factory gage feed) and splice it into the supplied loom, also a black wire was tied into the black factory wire (tank ground) the only other wiring was to add power from the fuse box. The bed rails are Bushwacker, I believe.They are attached with tape, the only thing I did was try to keep them tight on the inside where the trusedo rails would be. Definitely a warm wether project, even with a heated garage the tape and rails were a little stiff.