I feel like I’ve read plenty about the historical materialist understanding about how the US constitution was formed and its class characteristics, but a lot less about the actual act of declaring independence. I do know how a bunch of the founding fathers made fortunes from land speculation via genocide and stealing indigenous land; and how the Brits wouldn’t let the yanks do that because they didn’t want to start another incredibly expensive war with the native peoples. I’ve also read of Gerald Horne’s thesis about how the founding fathers were worried that GB would totally outlaw slavery. I have a lot respect for Horne, he’s great but frankly I think that theory has little to no concrete evidence supporting it. But those two are the only materialist analyses of independence that I’ve seen so far.
It wasn't just the potential cost of another war with native peoples, it was also their reduced ability to control or extract wealth from inland colonization compared to the coast.
I find the fear of abolition by the British somewhat hard to believe, the slave economy of the 13 colonies at the time was predominantly tobacco (and sugar elsewhere), which was waning in viability as the founders saw it. Meanwhile the abolition movement in Britain barely existed at the time of the American revolution, let alone being seen as an imminent prospect in the lead up to it. Even for decades afterwards there was far more British focus on opposing any continuation of the Atlantic slave trade (something the USA actively joined them in) than abolition of the practice itself; after all by then the vast majority of slave ships were destined for their rivals in South and Central America, while the British colonies that used slave labour were self-sustaining.