First off, I'm a building designer. There is no license required to design buildings and projects exempt from the requirement of plans & other documentations/specifications be prepared by or under the supervision of a licensed architect and/or engineer.
Some jurisdictions may require certain drawings or otherwise considered complex in nature to be prepared by an architect or engineer. However, this is often a discretionary of the building official of the local AHJ. However, when a building or project is statutorily exempt under the architect or engineer's licensing laws like SFRs and occassionally some small MFRs, a building official may consider validity of a CERTIFIED building designer in a judgment call. What is a certified building designer? A building designer that is certified by a building design certification. In the U.S., there is pretty much only one actual building designer certification. That is the NCBDC CPBD certification. NCBDC is an independent council of the AIBD.
The certification is undergoing significant revamping as it undergoes ANSI accreditation process. In part of the process is for making the exam more robust, justified cut-scores, subject matter validation which includes building codes in the examination. With this in mind as well as any ICC certification a person may have as a building design professional may be considered by the building official. This is why it is important to establish a good, professional repport with the building department. A building official is going to consider whether or not you have a sound understanding of the subject matter while that statutes of law ultimately trumps discretion but the building codes often allows for a range of discretion.
If your project is exempt from an architect's stamp, a professional building designer would not need an architect's stamp on those projects. They may need an engineer. Choosing the appropriate consultant is part of the job. Nothing is meant to demean architects. Clients just aren't going to pay twice for essentially the same service. They aren't going to pay an building designer and an architect to do the same thing. That is like paying two people to prepare what is essentially 'architectural floor plans, elevations, sections, interior" even though as building designers we substitute 'architectural" with the words "building design". It is basically the same thing for what matters.
In Oregon, where I am, I am liable for the plans I prepare.
On a set of permits, you would more likely scratch out 'architect' and write in 'building designer' or 'designer' and put the designer information in where applicable. If you are a certified building designer, you would have an CPBD stamp/seal and have your certification #. Just don't represent it has license number.
I'm suggesting you certification over architectural or engineering licensure because you don't need it nor shouldn't. You can simply partner with an architect or engineer or subcontract the engineer as a consultant. Unless you are willing to invest 8 YEARS of full-time academic study & experience or experience and taking considerable time studying to take the exams. I don't think as a business owner, that you would necessarily want to close up business which makes you money and pay the bills to do all that because it just isn't like you can study architecture at architecture school at part-time level which would take you even more time. In which case, you can end up spending 16 to 20 years to get through all that and still run the contracting business. You would have to shut down the contracting business to be able to study and focus on architecture school and internship.
I know the pain. It don't know if it is viable for you but NCBDC certification is probably more achievable but it isn't the same thing as an architect/engineer license. It is a certification and can be used to relieve concerns of some building officials/departments because ultimately they want to be sure the plans are properly prepared and that you aren't just a schmuck submitting garbage.
