The correct way to batch transactions in one is to use "pay-to-many" with all of the recipient in one transaction.
That way, those 5 outputs wont have to be included one at a time via RBF on each.
Just type the recipients int he "Pay to" field like this:

For the fee rate in your method (utilizing batch rbf transactions), that relies on the RBF replacement rule that the fee of the replacement should pay for its own and the replaced transaction(s)'s bandwidth.
So its minimum is not a simple 0.1 sat/vB increase but calculated from the 1st transaction' absolute transaction fee plus the replacement transaction's size and minimum fee.