Try something like:
[Merlin, Merlin Tackle]
Overdrive Injector System I
Overdrive Injector System I
Warp Scrambler I
1MN MicroWarpdrive I
Warp Scrambler I
Target Painter I
E5 Prototype Energy Vampire
E5 Prototype Energy Vampire
E5 Prototype Energy Vampire
[empty high slot]
[empty rig slot]
[empty rig slot]
[empty rig slot]
Essentially you warp in, approach target and orbit at 2.5k/s - draining 10 cap/s.
Keep the orbit nice and close - 500-1000m - and he'll have a problem hitting you with either missile or guns. But conversely so will you. Not much of a problem as the primary purpose is to tackle and to stay alive.
Additionally with the speed it's a good alt/afk fit - just keep the orbit nice and tight.
The above is a fairly tight fit - but if you want to fit weapons also:
1) Drop a vamp
2) Go for blasters (Light Electron Blaster x2) as they have better tracking and fitted with antimatter (shortest range)
When tackled vs a Domi then orbiting at 1k should give you 31dps, against another frig you'll need to be at 1700m to get 21dps.
The above setup is cheap (around 3m) or with guns it'll cost around 2.5m.