roof leaks

Need a cheap way to fix leaks on my 5th wheel roof, checked fixing it and $2,000 to $4,ooo. There must be a tar or rubber paint to fix it, tried that new sealer in a can, sprayed it on still leeks, may be not thick enough. Its covered right now for winter, trying to keep it dry. Need ideas for this old fart that's got c.o.p.d. but I can still do it slowly. Really need help on this.

Thanks for any info or ideas.

klink