Thank you so much everyone for your advice and willingness to share your knowledge despite me not being and RV owner.
Stevebaz, my cracks are narrower than that but probably just as long. What you posted looks like the easiest solution, that's what I'll try first, instead of buying mat and resin, like the above linked tutorial thread shows.
charlsara, I'm not looking for a show piece, so I'm going to give it a shot myself. I have patience, hopefully that will serve me well.