Either way, it shouldn't have been on the "pro-leave" campaigners to implement a plan. That's for the government of the UK to do now that it's been "decided" that they should leave.
They can't even say what they want, except perhaps for the absurd fantasy where they get all of the benefits of the EU and none of the obligations.
Problem with this is it raise the bar. Who controls the resources available for plan-making?
The same thing happens in research, where certain results can be suffocated through lack of funding.
The government that raised the referendum should have prepared for either result. Seems the government figured it wouldn't survive being in power with a brexit result anyway (and might not want to), so why allow a plan to happen - the more the next party struggles the better...
Here's a large boulder that looks like it might/mightn't be about to fall over a cliff.
I super-glued your hand to it - the glue's not completely dry yet, but it sure will hurt pulling your hand away (might take off some skin, you could bleed to death!) - better not do it?