If your coach is equipped with device called B.I.R.D. made by intellitec it will charge your chassis battery while plugged into shore power. My thor motor coach came with this device already installed in it.
If your coach does not have the "BIRD" device, you can install a device called "amp-L-start" . This device will also charge your chassis battery while plugged into shore power.
If measuring your trips in 'weeks' - I wouldn't expect any issue with the chassis (truck) battery - assuming a good battery and no load.
If your unit has a chassis disconnect (as my 2000 Infinity did) - I also used the disconnect when parked to insure no load.
My 2014 Hurricane no longer comes with that switch..
dstankov - I've never seen an answer beyond 'it depends on model' as to whether the chassis battery is charged by coach.. I tend to suspect mine is - as I inadvertently used a 12v chassis socket for quite some time on our first trip - and when I discovered it was chassis powered - checked the battery voltage - and all were fine.
My searching never found a definitive answer.
I carry a charger with me - but only used it when an electrical problem prevented proper charging of the chassis battery when DRIVING (on the 2000.) A whole different issue as I limped home from that trip...