Hi Chris,
do you know krpano multiresolution panorama? If not, you might like it. Here is one:
krpano - 16-07-25_Urpin_APG+LR+PS_v2
It has only 250 mpx as it was made with Oly 12 mm. But if you used 45 mm for example, it would have more than 3 times higher resolution than the one above.