We need to split two issues here.
1. Are fighters useful in Trav, and
2. Should the container for these fighters be your battlewagons.
Im inclined to answer 'No' to 1, because of the problem that the picket/scout role requires any fighter to either be recovered or left if the main body needs to jump. You are simply better off using some variant of the 100 dton type S scout for that picket/scout role.
Regarding being a screening line, I find it difficult to pick a range where fighters can be both useful, and beyond the effective range of bay weapons - and to be effective in space, any screening fighter will need a fair amount spent on computers or sensor gear (Im someone who translates High Guards 'Computer' as 'Computer+Sensors+Ecm+Eccm' btw). If you are losing an expensive sensor package every 300 seconds to a 50 dton PAW weapon on some cruiser or other that shrugs off the tertiary armament fighters carry, thats a bad trade.
If you're losing them to turret weapons, then thats even worse.
Regarding 2, if fighters are effective, then you want to be moving them around on vessels optimised for them, which in Trav terms means some sort of closed structure vessel that has fighters and fuel shuttles clamped on everywhere, and finds somewhere to hide in battle (note doing a jump-1 with a pre-planned 'come back' rally point deep in the outsystem counts). It doesnt mean crippling your battlewagons with internal space being spent on fighter bays that still need to be pushed around at multiple gees and protected by deep belts of armor.