Yes it is attached to the top of the ladder. I bought a piece of 1/4" aluminum 6" x 3' to make the mount and then used stainless U bolts to attach it. The wiring runs down one leg of the ladder and enters the back cover at the lowest ladder mounting bracket. I took out the tail lights and it was easy to fish the wires to the side where my desk is and bring them up in the desk/entertainment slide, alongside the other wires that come up there.
I find that the converter creates quite a large amount of noise on HF and I have to turn off the breaker to that when operating the HF/6 meter Kenwood Tranceiver. I have run 12V power from the batteries to the desk to power my ham radio's.
You had also asked about what frequency to monitor when traveling. I try to monitor local repeaters as I travel so sometimes I am scanning the programmed repeaters in my truck as I drive. I don't know of any particular simplex frequency that is used by hams when traveling. Here in Canada the truckers use 3 frequencies in the VHF band and they are called LAD 1,2 and 3. I sometimes monitor them up here but the language can be pretty raw at times. I notice those frequencies are not used in the US by the truckers, at least I have never heard anyone on them. They are not in the Ham band by the way, and I am only able to transmit on them because I have commercial VHF equipment that I can program those and other frequencies into.
There are Nets on different bands that a lot of traveling hams check into on HF, particularly in the winter as they are keeping in touch with folks back home and other friends that are traveling as well.
If you are mostly interested in VHF then make yourself familiar with IRLP, that is Internet Radio Linking Project which links VHF radio to the internet and there are Nodes all over the world that you can contact other hams using only a handheld as long as you are close enough to access one of the nodes. Here is a link to the website. The creator Dave Cameron is a good friend of mine and lives here in North Vancouver. He is a ham of course. VE7LTD
IRLP Link: http://irlp.net/