Solar -> Supercapacitor efficiency considerations
For a hobby application I agree with you.
There are though, quite a few variations with cell type, temperature, cell internal resistance that could significantly change your performance.



Looking at the above graph, the Voc is roughly 1.19 x Vmp (max power voltage)
So sizing the array for max voltage will mean that you are very roughly 19% lower voltage at max charging rate.

That's not so bad, but then take temperature into account.



If you scan the Net, you will see manufacturers ratings of -0.3%/deg C to -0.9% deg C.
Take the middle ground and look at a +25 deg C change;
-0.6%/deg C

-0.006 x 25  =  - 0.150   ( - 15 % )

Summary so far;
-19 %  max power to Voc
-15 %  for temperature
-34 % overall

0.34 x 0.75 volts = 0.25 volts less

So this is what you are left with;

0.75 volts - 0.25 volts - 0.5 volts.

It is important to understand that all these numbers given depend heavily upon the many other factors like solar array material, architecture, percent of full illuminatioon, etc.

See next curve.



We haven't even talked about internal cell losses ......

Anyway, at the end of the day, you can experiment as you have mentioned, but do put SOME PROTECTION for the supercap.
At least have a dumb zerner diode to clip excess SA voltage and be sure to heat sink it well. Put the diode directly across the incoming array connections.

Hope this helps.