Although after a certain point in the SG timeline IMHO, SG crossovers with B5 become less interesting because of the massive power disparity.
I think you might like this one. Its more of a character driven story.
One idea I had for a B5 crossover was that the Centuari found the 12 Colonies of Kobol instead of Earth. As a result, the first cylon war kicks off as the Centuari are getting involved politically with the colonies. Thus, the first war ends not with a ceasefire, but with the cylons grabbing whatever ships they can and running for deep space where the Centuari can't follow, and the colonials don't have the resources to pursue.
Then, when the Dilgar war kicks off decades later, you have a human polity that has weaker ships with a different type of FTL instead of interceptors as their precursor tech. Most of their B5 tech would be Centauri knockoffs, so energy weapons yes, artificail gravity no. So the humans would take a lot more damage in the Dilgar war, and would probably end more in an armistice than a victory.
When the colonials finally get around to doing deep space exploration, turns out the cylons are still out there, now as a Minbari protectorate, and the colonial attack on the cylons is what kicks off the Colonial/Minbari or second Cylon war, depending on your perspective. Needless to say, it goes poorly for the humans, but the Minbari once more stop before the 12 colonies are fully destroyed.
I like the idea of the Centauri meeting the Colonials but not with Earth getting the Shaft and losing out. But I could see the Centauri pursuing a relationship with them independent of Earth.
Speaking of. I think you might like this one.