Start farming runs tonight, and never stop doing tree runs forever. Even when you are 99, it's worth it to do maple/pineapple or higher runs because it's like 600k exp/hr, which will help your total rank a lot. You'll easily get farming in 2-3 months if you do 1-2 tree runs every day.
Slayer will definitely take the longest, but it's not as bad as it seems. 66-99 slayer will result in loads of effigies, probably close to 100. Assuming you open every effigy yourself, that's 100k-120k exp per effigy, meaning a shit ton of EXP in extra skills just from training slayer. It looks like you can open most effigies except for Sum/RC ones, which is good. If at all possible, spend the dragonkin lamps on Runecrafting (and try to get RC to 91+ to open effigies with it, as well), since getting to 99 slayer will easily result in enough charms to max summoning.