If they are open, I'm using them! (although we have back up!). Not worried about showers, those places are full of soap. TBH, I am more worried about catching a tummy bug whilst camping than Covid. I suppose the biggest chance could be going in a loo/shower cubicle if any airborne particles are still there.
I actually think now that water points on campsites are going to be the most possible place that one might touch a surface that has Covid on, as it's not somewhere where there is opportunity to wash hands afterwards, or something that you'd think of doing (unlike the loo).
I am going to have a bowl of water at the tent, with a little dettol in and soap. When we come back to the tent after any reason, wash hands in that.
But, I personally think that catching Covid is still quite unlikely. You have to have that contact with someone who is infected AND is shedding the virus in a form that is infectious, and then get that into your own body. Symptomatic people should not be travelling. There is currently little scientific knowledge if asymptomatic people pass the virus in a way that is would cause a bigger reaction in others. Presymptomatic people could be a problem, but the rates of community infection (not hospitals/care homes) are low, and recent cluster incidents have focused on work places, where people have had close contact for 8 hours or so.
So, for me it's not entirely risk free (nothing is), but I think I have less risk from catching it on a airy campsite, than I have at work.