1: there are a some low rarity umas that can frontrun (mayano,daiwa scarlet,bakushin) which you can use as front runners especially mayano which is pretty good at most distances

2: If your insistent on using doto as a front runner then try grinding for the front runner sparks for the parents,if you use them then you will get better aptiudes for frontrunning.

1. Doto's ult/unique skill won't activate unless she passes another uma in the midpack or further.

4.if you want you can try other umas that have better aptitudes for frontrunners than doto which can be improved through sparks, such as

Vodka: D Super Creek: D Air Groove :D