Brian,
You have entered into an area which is subject to a lot of debate at present, given the repeal of the fee-based brokerage accounts rule (following the FPA vs. SEC decision of March, 2007), the repeal of the Dec. 2005 no-action letter, and lack of SEC guidance since then as to whether financial planning is subject to the Advisers Act.
Interestingly, it appears that SEC Release 1092, available at http://www.securities.state.oh.us/SECReleases/SECRel1092.pdf, may be the controlling authority right now. This release takes a somewhat expansive view of the application of the Advisers Act to financial planning activities.
Another resource can be found at http://www.liftburden.com/whoRIA.pdf, a nice little piece by The Consortium, which essentially explains 1092 and when registration is required.
I believe that "portfolio construction" - if applied to individual client portfolios and advice on same is hence provided to clients for compensation in some form - is clearly providing investment advice, and requires registration as an RIA. Note, however, that there is a de minimis limit in each state, but even then certain criteria may need to be met - such as not "holding out" as giving portfolio/investment/financial planning advice. My conclusion is the same regardless of whether any products are (or are not) recommended.
Others may have a different opinion, or additional insight.
If you determine to proceed with such activities, but not to register, I recommend that you get a written opinion from a securities compliance attorney (not a general practictioner) to the effect that, based upon the specific facts of what you are doing, you don't need to register. (Having a legal opinion does not necessarily protect you, but it helps in several respects.)
Ron
Ron A. Rhoades, JD, CFP(r)