Depending on the junction you're turning off the A30 onto, I'd possibly be looking to be dropping off two markers. If safe, I'd drop one off on left verge / road curbing about 50 metres from the right turn junction and for that person to be pointing right when following riders approach to indicate the right turn off main road ahead.
The second bike following you making that right turn I'd drop off a few yards (if safe) along on the road you've turned right into.
Right turns off a main road are invariably the more awkward ones to mark ... but dropping of 1st marker on left before junction to point out the right turn ahead means you are less likely to get riders just riding past the junction if they miss the person you have dropped off after making the right turn.
Just my thoughts really ... but as I said it depends how open the right turn is and therefore how easy it is for riders approaching the right turn to see a marker that has already made the turn. If group all relatively together then people will see where bikes in front are turning ... the danger is where there is a gap and a person just rides past the turning. The first drop on left before junction should minimise the chances of this happening.
Good luck.
