Why wouldn't you try all kinds of combinations? This is one of the fundamental ways design is performed.
Design is inherently an inverse process -- we start with desired performance and work to find the system that achieves it. In rare situations, we can analytically solve inverse problems directly, but most of the time, we end up having to use some sort of guess and check or repeated evaluation.
In some cases, people have run many solutions before us -- we can use their results, charts, curves, or experience. But you have to find that set of data or knowledge and make sure it applies to your situation. In this case, you're really relying on someone else running lots of combinations.
If I were to assume you're at the start of your Senior Design project -- let me assure you, running a lot of cases and doing a lot of iterative guess and check is going to become a very familiar activity.
You say you already want a planform with poly-taper -- rectangular inboard and simple taper outboard (Like a Cessna 172). The dihedral will not substantially effect the load distribution (how close to elliptical). So why not set up a tool and compare wings with taper of 1.0, 0.8, 0.6, 0.4, 0.2, 0.0.
If you use zero twist and an un-cambered airfoil, you can isolate the effects of the planform. Run all the cases at the same angle of attack. Record the lift and drag coefficients. Both will be different, so you will want to process them into equivalent induced drag factors -- either Oswald e or the K in CD0+KCL^2. You know that the zero angle of attack case should result in zero CL and zero CDi.
You can also plot the six lift distributions on top of one another. You might also want to plot the lift coefficient distributions and compare them.
For this, you'll want to use AVL, Tornado, XFLR5, VSPAERO, or another similar tool.