I don't know about this.
Around here all of the people who do backhoe work for hire have ~100 hp machines. I think the charge about $50/hr.
I know for sure the when my neighbor had his retaining wall fail, my 110 could not move the 16 cubic foot concrete blocks it was made of to re-stack them. The backhoe he hired moved them with no problem at all.
While I don't doubt that you could do a septic installation, or a culvert with a 110, your productivity is going to be a lot lower than a bigger machine.
Unless you specialize in limited access applications you are not going get many return calls, especially from house builders.
If you want to stick with JD, think about a 310.
I haven't looked into this a lot, but the most common machine for small, independent operators is Case in this area. The bigger excavating and paving companies have a lot of JD backhoes. Whenever I see 8-10 machines lined up for a job, it is a good bet the backhoes will be Deere. OTOH, one guy hauling his machine out to a site behind his dump truck is almost always going to have a Case.
Very good information!