Hi @Burns-bass Similar to you, have an hour or so most days, and work from home surrounded by my basses.
Came back to upright last Jan after years away. Personal experience has been timing and general rhythmic technique (ghost notes, raking etc) has come more naturally from years on electric, but it's intonation that's the beast.
Still a long way to go but some things that have really helped;
1) Videoing - both gigs and at home. Big, at times painful, gulf between 'real and feel' intonation!
2) Drone work against major and minor triads. Great tutorial here from Frode Berg. Every practice session starts with 10 mins of this.. Has helped hugely with both intonation and improvisation.
3) Modacity app. Use daily, been invaluable in structuring practice sessions and maximising what time I have.
Had one 'in person' lesson to make sure technique was sound, but have since worked through some paid-for courses on DiscoverDoubleBass, some excellent content on there. Good luck with it all.