The good people at https://www.adventurecycling.org/ have routes developed by cyclists for cyclists, so I will be following their route along the Pacific coast from Seattle to Tijuana.
Then, the plan is to go down the Baja Peninsula to La Paz, take a boat to the mainland, and then bike to Guadalajara. From here I can catch an inexpensive flight to Cancun on the other side of the country, and bike down the east coast into Belize. From there I haven’t decided if I will bike through Honduras into Nicaragua, or bus from Belize City to Guatemala City, and then bike through El Salvador into Nicaragua. I am leaning toward the latter.
Either way though I will end up on the Pacific coast of Nicaragua where I can bike south through Costa Rica and then home, unless my husband meets me in Nicaragua and we decide to bus home together, an likely option since I have already biked this part before.