Books for DIY maintenance of a 2005 Itasca Sonova?

Most books for things like this have been replaced by YouTube videos. You can find most anything there, just make sure that the person posting the video appears to know what they are talking about. And I know you want something specific to your motorhome, but most RV stuff can be fairly generic. For example you're looking for chassis maintenance info on your specific motorhome make and model, but many many other makes of motorhome will be on the exact same chassis as your motorhome. I have a National Tropical, but it sits on a Freightliner chassis with a caterpillar engine so when I look for maintenance stuff for the chassis, I'm searching Freightliner and Caterpillar, not National Motorhomes.

You can download the actual service manual and chassis guide HERE

Unless I totally misread the OP He didn't mention whether his Sunova was built on the Ford or Workhorse chassis. If it's built on the Ford F53 chassis manuals are available in paper and CD format. A good place to look is E Bay. They generally sell for between $35.00 and $50.00.

If you go there to look be sure to get only the genuine Ford CD's, and make sure the one you get covers the F53 chassis. Most aftermarket manuals lack the details necessary to complete most repairs.

Here is a place to start:
2005 Itasca manual
Workhorse owner's manual
Workhorse chassis manual

The chassis side of the rig isn't much different than a 2005 truck just bigger in overall size/weight. The prospect of finding anything published for specific make/model coach is slim. Generally there is very little difference regarding procedures or check points. There are a few items than the average car/truck vehicle owner probably never touches that will need attention such as flushing the brakes, but how to do it isn't much different than a pickup truck.

First place to start for the chassis is the owner's manual and the recommended maintenance schedule. Review the list, your coach history if you have it and get on a schedule. When you hit an item you're not sure about search YouTube, RV forums and truck forums. All are excellent places to gain knowledge and finding the simple tricks to make the job easier. The learning curve isn't as steep as you may think.

For example my coach is built on a 2006 Ford F-53 chassis which is very similar to a Ford F550 truck and F350 pickup. A few items are scaled up in size and capacity but the maintenance procedures are generally the same. The engine and transmission are identical to the F350 but axles are different. Break the systems down into individual sub groups and work from that direction rather than one overall shop manual and you might have more luck.

The trick to keeping a coach happy, the various systems working and expand your knowledge and understanding of the coach is to use it. Nothing will shorten a life of a coach quicker than parking it in the back corner of a storage lot for months on end unused and neglected. Make an effort to get out once a month even if it means heading back to the local camp ground for the 10th time after work on a Friday or even just camping in the driveway on a Saturday night.

Good luck!

As close as you will probably come is a Chevy workhorse manual,
www.ultrarvproducts.com/Workhorse-Manuals