I did as high end a system install as possible and it was overkill. The 200 Watts and MPPT controller recharge my two 110 AH 12v batteries in 2-3 hours, winter or summer.
Two places you can save time and money. First is to install a single panel and try to use the Lance factory wiring. It is 12ga which is not ideal but it is good enough. It is better with a 34 Voc panel than a 17 Voc panel as there is less current loss with the higher voltage but not a big deal if all you put up is a single Kyocera 140 Watt panel. The Kyocera and the 100 Watt panels from AMsolar.com are narrow and so fit in the limited space found on camper roofs and not going to be shaded by anything on the roof.
The Lance wiring will go to a cabinet space where you can install a small charge controller. From there the wiring will run near to where the battery is located and you want to install a switchable circuit breaker so you can switch off the power from the panel(s).
One easy place to install a solar panel is on the roof rack. I could not do this on my camper as the roof rack is directly over two of the roof vents.
You can save a great deal by going for a system that will be 80% as effective and cost a third of what a premium 99% system. It really will have little impact in real use when it take 4 hours to recharge the battery or batteries instead of 3 hours. You cannot do anything with the extra current produced once the battery bank is charged.
Do add a monitor like the Trimetric. The Lance gauges are about as useful as using a dip stick to know how much gas is in the truck's fuel tank.