Has anyone had success getting an HG+ child of elementary age (ours is entering K) close to fluent in a foreign language without any of the obvious supports (parents are not native speakers, no nanny/au pair, no language instruction at school, no long-term travel, etc)?

I want my 5-year-old to get language exposure now based not just on the benefits for brain development, but also because I have a sense that he is fascinated by language and would really enjoy it. I haven't found lessons that easily fit into our schedule and I'm not really sure that something once-a-week for 45 minutes would be of much use unless we have a real plan of how to reinforce it at home.

Spanish is the most obvious choice. Both parents can moderately read it and somewhat speak it (but our accents are terrible and we are long out of practice). Our neighborhood school has a dual-language program but our son will probably not be able to get spot for that (it was lottery-based). He does at least have a spot in the G&T classroom.

I'm mostly a stay-at-home parent so logistically the easiest approach would be to do instruction for him and his 3-year-old sister myself. He can already read most anything in English and I think I could get him reading basic Spanish on my own. But I worry he would end up with the same issue that I have in terms of basic literacy but few conversation skills - not to mention that I would be transmitting a really bad accent. But perhaps this is just the excuse I use to justify not having done it already.

I would love to hear from anyone who has actually made it work.