You really don't need to have a heated and covered space to work in. You need some dry weather so you can start with a camper that is dry. You need moderate temps. I don't know if there are specs for Dicor but I have worked in 50 degree weather with no issue.
There really is little or no "drying" time needed with Dicor. It merely needs to skin over in order to handle rain. It will not wash off even if applied just before a rain.
It sounds like you have not worked with Dicor or a similar sealant. I recommend starting on the roof with leveling Dicor. You can experiment with techniques to get a smooth, professional looking application. Get some mineral spirits, disposable gloves, and LOTS of cheap paper towels. You can use blue painters tape to achieve clean edges or just use a finger dipped in mineral spirits to smooth the Dicor. On the roof I usually do a complete application and then a second coat. Take your time and exam and deal with every square inch of the camper. This is pretty much a one time job. Dicor sealant can last for a great many years or even decades.