You need to prowl around my web site for awhile.
The ladder of any RV is one of the poorest locations to mount antenna, as the ground losses are very high. Grounding the antenna to the frame doesn't help. In some cases, you're better off using the ladder as an antenna driven with an auto coupler (tuner). However, that depends on the ladder, how it is connected to the RV, etc.
Remember too, the ATAS is one of the lossiest, remotely-tuned antennas. Even with a fairly good ground plane under it, the efficiency is under 10%, except on 10 meters where it's about 15%.
There are some photos in the gallery of other RV and motor homes, but the truth is, they are suffer as there just isn't a decent place to mount an HF antenna, drilled holes or no.