Fastjack
Chieftain
Mortars are the best plan for a modern ranged unit. To the person who said mortars are included in infantry units, that is a per army decision - and therefore is up to you to simulate 
Also, if snipers were included, the -20% combat strength is a little dumb imo... will get complicated and confusing. It would be much better to assign the sniper a relatively low ranged strength, but make it "pin down" units, making them unable to leave the square they occupy during their next turn.

Also, if snipers were included, the -20% combat strength is a little dumb imo... will get complicated and confusing. It would be much better to assign the sniper a relatively low ranged strength, but make it "pin down" units, making them unable to leave the square they occupy during their next turn.