How much power is your solar panel rated to give?  The info the solar panel makers give is generally best case, so if there is haze, or clouds, or its not lined up to take advantage of the best angle the actual output will be less. Determine if you will have enough solar energy to charge your battery to enable to you run your radios for the estimated time each day you are going to want to operate.  Be sure to plan for a few cloudy or even rainy days between sunny days, or have a contingency for that (charge it a little while from the car or something handy).

 Also, importantly, heat makes the panel less efficient.. which is bad as you will notice they are all a black panel. What gets the hottest in the sun? Of course its our panels.
So, its best to mount them some place that has air flow behind to help cool them. I have a 120 watt folding panel, and I try to not lay it on the ground, as it gets warmer with no
under side air flow.   On summer outings (up to 40C at times) it is very noticeable the heating effect, where in winter time (as low as -20C) , it works a lot better.   

I hope those are some ideas that will help with what you are asking. 

73  Arn