Where will you be traveling?

In the southern USA there is about a 10-12% loss if you simply lay the panels flat instead of tilting them optimally. You have more loss the further north you go.

Edit: my math is suspect. might be more loss. checking.

Edit2: I got this formula for the flat efficiency vs optimal tilt - cos(x) where x is the latitude of the location. But then it got confusing with tilt of the earth, time of the year, time of the day.

But if you have one panel at the optimal tilt and another panel of the same dimension flat, the flat one will produce about cos(x) as much power as the tilted one.

In Cleveland OH, at about 41.5 latitude, a tilted panel will be 100% and a flat panel will be about 75% efficient.

In Austin Tx, at about 30.25 latitude, a tilted panel will be 100% and a flat panel will be about 86% efficient.

If your application is dependent on these numbers, do the math yourself. It has been a loooooong time since I was in trig.