I probably would walk away on that one. We dealt with fiberglass cracks on our previous Cedar Creek. 1 under a window, 1 in a outside kitchen door and went 3 rounds with the front cap. The fix under the window was successful. After a fix to the outside kitchen door, it reappeared and they had to replace. On the cap. Fixed once, reappeared, replaced whole cap, more cracks reappeared in the same place. Fixed that cap and soon sold the rig. They never could really figure out why it was cracking. With our previous experience with cracks, I'd walk away. Unless you know exactly what is causing it and can fix it, it'll probably come back.
Do you have any pictures of where it's cracking?
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)