We bought this 1981 Dolphin at a great price, but the roof is a bit funky, they've put asphalt roofing sheets on top, and it's definitely not totally waterproof, and there is at least some leakage happening in the cabover area. My question is, if we want to recoat the roof with an EPDM roof sealer type coating, should we just pour directly onto this stuff, or should we try to rip/scrape it all off first?