Mosaic Manual Rotator Checklist?

for simple accuracy I use a Wixey Level which I Velcro to the top of my camera/scope ( I remove it once the plate solve/rotation is confirmed as correct)
Here is a link to the level I use.
https://www.amazon.co.uk/dp/B00CEXUC22/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=569136327&pf_rd_s=lpo-top-stripe&pf_rd_t=201&pf_rd_i=B00OTUTRFG&pf_rd_m=A3P5ROKL5A1OLE&pf_rd_r=PSJ442Y92RANFQXCWRQV
SGP will indeed tell you to rotate X degrees clockwise/anticlockwise. At this point just zero the level and rotate accordingly..it may take a couple of goes depending on how tight you set your tolerances.
I have mine set at 1 degree and it doesn't normally take me more that 2 iterations to get that close.