The problem with epoxy for an exterior repair (gel coat issues aside) it that it turns from yellow, to amber, then brown when exposed to UV (sunlight)
You can mitigate this somewhat by mixing pigment with the resin - but the color won't be stable. You could have a perfect match the day you did it, then a month later, it'll be a different (browner) color.
Given that the bottom job is on the bottom, you could probably get away with using the WEST 105 as long as you were really careful not to get any on the outside flat of the hull and minimize the coverage on the inside. Masking tape and drapes are your friends.