I bought the US-made one because the delivery time was much faster than the UK-made one 
It took a few weeks.
IMHO the cockpit cover is really vital. Mine is used virtually every time I park the plane anywhere. By excluding sunlight and keeping down the temperature rise, it makes a huge difference to the condition of the cockpit after some time. My plane still looks fairly new inside after 14 years.
One issue with wing covers can be that the static wicks get in the way of simply sliding the cover on. I know one pilot who had the complete set of covers made and gave up bothering because it was so much hassle. But obviously a full cover will be better than nothing if you don’t have a hangar.
Most owners of something “nice” will not locate their plane at an airfield where there is no hangarage. This point seems to be lost on airfield operators who wonder why their airfield has gradually filled up with wreckage.
I haven’t used this guy but I happened upon a flyer at EGTB. WWW.DAVESCUSTOMCOVERS.CO.UK
The other thing is to keep a bag of silica gel in the cockpit.
Even better…and it costs one pound.
That’s implausible, IMHO, because the 0.5kg bags I use absorb about 40g of water. I have checked this by weighing them. They might absorb more but more water won’t get in from the free air in the cockpit, at the temperature in question, even if the RH in there was 100%.
Speaking of dehumidification: The book Owner Assisted Aircraft Maintenance describes an interesting and low-cost DIY solution for an engine dryer. Here’s a quick description:
As long as a wooden aircraft is kept in a dry well ventilated environment it is unlikely to have any problems with condensation, wood being a good heat insulator tends to change temperature at a much slower rate than metal and so is less subject condensation.
While dehumidifiers would help metal aircraft I don’t think that they are much use inside wooden aircraft.
I use the silica gel really for the avionics, and to keep the inside smelling fresh.
I did a measurement with a handheld RH meter and found that one 0.5kg bag drops the RH by about 10 percentage points, which is a huge difference in terms of condensation potential. The bag lasts a week, no more.
Currently I am in a hangar with no doors so one has to do what one can do…
