A compost tumbler is what we have in our chicken yard as well! They are pretty reasonable and keep smells contained! FCMP Outdoor IM4000 Tumbling Composter, 37 gallon, Black https://www.amazon.com/dp/B009378AG2/?tag=backy-20
There are loads of DIY compost tumbler tutorials online. I think I made mine for under $20.

) and will refresh your pen in no time flat!!
(also 