I am not in-game, how many limpets ? And do you refuel them or one time use ?
EDShipyard has the 1.3 features. Looks like a 1D controller is optimal for exploration (low mass) as speed of transfer and range would not be critical - this will transfer 1 tonne of fuel at a max range of 0.8km. I think the limpets take up cargo space but you only need to get the stranded CMDR to the nearest scoopable. Which means that you need to know how far they need to travel and what sort of ship they are in to work out how much fuel they need. Get that wrong and you could end up with two CMDRs stranded without enough fuel to get to the nearest scoopableSingle use I believe, the bigger controllers e.g a1 can control 1 limpet at a time I believe a5 can control 4.
A quick build to test the weight of kit: http://www.edshipyard.com/#/L=70g,,2-5K6u7_6u6u8S8I,5225fa05UmpU2jw2UI
EDIT: BTW, limpets are one time use - they go bang in a satisfying way