I actually find it easier to play over slower backing tracks because that's how I started soloing - over slow bluesy backing tracks. Any I - IV - V progression is easy to play over.....the hard part is playing an ORIGINAL solo. We're all influenced (consciously or unconsciously) by the guitarists we listen to . You listen to BB King, you're going to be playing lots of fills, heavy on the vibrato. You listen to Paul Kossoff, it's easy to tell he was influenced by BB - fills, vibrato, lots of BIG bends, but at the same time more use of distortion and more trills. Same goes for Peter Green - easy to tell he and Koss were both influenced by BB.
At the same time, both Koss and PG developed their own style - they both carried the rhythm as well as soloing, whereas BB just played fills - I remember watching him on the U2 "Rattle And Hum" documentary saying, "I don't play chords." Whaaaat? You've been playing all those years and can't play a simple chord progression?" and thinking, well there's hope for me yet - I CAN play rhythm chords!
I'm still a very mediocre soloist....much better at rhythm guitar, so maybe I'm not the best person to be handing out advice here. I still find it easier to play a solo using a slide, whether I'm in an open tuning or standard. Having said that, playing slide guitar has given me a feel for the fretboard that sort of guides my fingers to where I want to be at the start of a solo in any key....once you know where the chords are (especially A-shaped barres, or one finger barres if you're in an open tuning) you'll know where the roots, fifths, sevenths and ninths are etc in any key, using that A-shaped barre (in standard) as a reference point.
I once did a lesson on here about the basics of using a slide in standard tuning - I'll try and find it later today (3:30 am, ready for bed) - you might find it useful. My suggestion would be, for now, buy a cheap slide and try experimenting around the D G and B strings....or even without a slide, try experimenting just one or two frets up and down from a one-finger barre across those three strings. It'll give you a whole new insight into soloing, as well as adding (warning - bad pun alert!) a whole new string to your bow.....
"Sometimes the beauty of music can help us all find strength to deal with all the curves life can throw us." (D. Hodge.)