Rainforest starts usually lack production, so building a Spaceport and completing space projects is going to be a slog unless you find a way to supplement your production. On the other hand, food typically abundant in cities in rainforests. To help offset the former and take advantage of the latter I'd get a religion with Work Ethic and grow the cities with Spaceports as tall as possible. A few well-placed Holy Sites with Sacred Path can also aid in the patronage of Great Scientists and Engineers.