To be honest, I think the third and the second goal are very easy, things you'd do anyway if you want to play a comfortable game. Maybe we should change the first goal into: build at least a city on X different "islands". IIRC, there are some islands SW of Lisboa, Ireland is probably still unsettled or empty enough, maybe there is some more space in Brittain, Sicily of course, and so on. So, would it be reasonable to ask them to settle at least 8 cities on different islands? (The code could be transferred from RAND of course)
I've never liked the goal of never losing a city since I've been playing RFC. It's not necessarily boring, but if you lose a city, you already know for quite some time that you've messed up. I can understand why certain civs can have these goals, Byzantium for example might be one of them that could be challenging, but overall there is no major accomplishment needed, since it requires a passive playing style. I don't know if I'm asking something unreasonable now, since I haven't done so many games as Portugal, but we could give them a goal like: ensure there is no Cordoban or Spanish culture in this area (which could be the spawn area). That could require the player to totally destroy both civs, or at least make sure that their culture simply never gets into the area. (On the flip, there is AFAIK always some culture of the previous civilization that doesn't disappear. So, it will never disappear unless Spain and Cordoba are destroyed. In that case, we could alter the goal to have at least 90% culture in the required area, or whatever is reasonable. I'm not sure whether it's possible to remove culture with espionage, but it would be fun if it is)
The third goal is very reasonable I think. Let's go with that.