Geocel Proflex is all I'll use. VERY good stuff. Just have to smooth it with finger dipped in mineral spirits or dawn / water opposed to just water. It sets up FAST, so only do short sections at a time. You'll be hard pressed to find a sealer better than Geocel.
John and Rebecca Dickson
Emma-8 / Little John-5 / Iva-1+
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)