After checking a bit of what can be found via the Internet, I am almost certain that you will be able to take your Christl line and the lines of their in-laws back to 1800 and even earlier. It will be quite some work for you, though. Let me comment on various aspects of your search.
1. The arrival record of Rudolf Christl at Ellis Island. This record can be found at www.ellisislandrecords.org
. Enter Christl as the last name and search. Also register at this web site. There is no charge. When you are registered, you will be able to see the manifest. The arrival record (manifest) of your greatgrandfather states that he arrived in New York on April 2, 1910. He is listed as a carpenter, age 48. This age was officially corrected to 49, and his manifest was stamped as "deported." As I wrote earlier, his closest relative in the old country is given as his wife Franziska of Haselbach, with post office in what surely is a misspelled Kollerschlag. Around his entry in the manifest, there are several other men arriving from the general region of Kollerschlag and Haselbach, most of them from Wegscheid and environs in Germany (Bavaria). Many of the travelers were on their way to friends in Milwaukee. As for your g-grandfather, the acquaintance he was supposed to going to, is listed as Joseph Kempinger with a detailed address in Milwaukee. Lastly, the record has some information about his looks, such as height, color of eyes, etc. His birthplace is given as Kollerschlag (once again very much misspelled). This information might be significant, as there are other indications which I will write about, that Haselbach became the residence of your Christl line only sometimes after the birth of Rudolph.
Please also check what else the Ellis Island records have on Christl arrivals. Do not limit your research to the spelling Christl but search also for Christel, Kristl, even Gristl, which are all the same last name in different spellings. Do the same when you look for your ancestors in other data collections. I did some checking and found a Katharina Christl, arriving in 1921, age 25, from "Kerschlach" in Bavaria" (must really be Kollerschlag in Austria). She was part of a group of nuns on the way to the US headquarters of their order ("scholastica"). Another arrival is the 1913 one of Maria Kristl, age 23, from Wegscheid. Her father is listed as H. Christl. The H might stand for Heinrich, as a Heinrich Kristl from Wegscheid is listed as arriving in 1914, age 23, his father's name also being Heinrich. This father Heinrich might have travelled to the USA himself in 1906, as there is the record of a Heinrich Kristel, age 40, from, possibly Wegscheid, who went to Lakawanna in Pennsylvania.
2. Geography. Have you found a good map of your ancestral Haselbach and Kollerschlag? This is an essential requirement for your further search. Since you said that your g-grandfather was not allowed to stay in the USA because of his age, it is almost certain that you have found the correct Haselbach among the many possible ones, and it is the Haselbach in the town of Kollerschlag in Upper Austria, district of Rohrbach in Oberösterreich. Haselbach lies southwest of Kollerschlag. Further west lies Wegscheid, after crossing the border of/to Germany. I recommend the official Austrian maps which are very detailed and accurate. At Kollerschlag, the maps include enough of Germany to completely cover Wegscheid and environs. Go to http://www.austrianmap.at/
. Enter the searchname as Kollerschlag, then select either the link under the "geographical name" or under the "political name." The first of the two choices gives you the most detailed mapping. Focus the maps also into the less detailed range so that you will get an accurate idea where your area of interest is located. Westwards and relatively near is the city of Passau where the rivers Danube and Inn join. In the other direction (ESE) it is not too far from Linz, the capital of Upper Austria. Not too far to the North is the Czech Republic, traditionally known as Bohemia.
I need to suspend my message. Will try to finish it tomorrow by looking at the sources for vital records and some findings.
Regards, Fritz K., Bethesda, Maryland, USA