I've tried using some of the freely available tools for making pork chop plots to explore the potential of transfers between planets.
But as far as I can tell, these really are not designed for and do not work so well for transfers that use very high (impulse) delta-V and are far from the optimal launch window. At least one states this explicitly.
I understand that very-high-delta-V trajectories do not have the same sorts of local minima as normal ones, but is there a free-to-use tool out there that can automatically do this cleanly? Especially if a limit of delta-V can be the input?