Yes, in series the partial shade on one panel will affect the output on both. But with a 25ft wiring run it's a "no brainer" -- you'll get half the voltage drop in the same gauge wire, AND you'll get effective charging more hours per day.

I have 8 panels; wired as pairs of 2 series, with each series pair wired in parallel. In the image below, the first two are a series pair, the next two are a series pair, and each pair is wired in parallel. The other side of the boat is a mirror image of that arrangement, and the two sides are in parallel.

Originally they were all in parallel and I estimate the overall output per day was boosted at least 20% when I changed to series/parallel.