AIUI the inclination-from-the-ecliptic difference between Earth and Mars is "maximally bad" this month, so you'd either have to do something fancy---or else refire S2 after a couple months of coasting.
I'm starting to be persuaded that the "fancy" orbit is just a "simple" apogee-at-Mars-distance elliptical orbit, and the inclination difference is going to be sold as a planetary-protection "feature".
Mars is quite far away at the moment - 16.15 light minutes distance, in a telescope 4.8 arc seconds, about 3/4 of the furthest it can get from earth. Visible low in the morning sky.
Opposition is July 26th, when they will be 3.22 light minutes apart and 24.2 arc seconds. Insight will launch May 5th to transit optimally.
If you want to make it to Mars, you'll wait on your launch to later this year. Now, if you want the long transit time with an encounter (no props to assist capture), you don't need to wait to May to do so, but you still need to wait.
(Yes you could conceive of an aerobrake by skimming the Tesla through the low atmosphere, possibly melting portions of it, which might lose enough delta-v to be captured into an orbit around Mars, but given that you'd like to minimize encounter velocity you'd have to wait close to a year and a half so as to launch and encounter Mars 180 degrees apart (too late for this opposition, would have had to happen many months ago - see more in
Earth--Mars Transfers with Ballistic Capture). As it's the wrong shape for entry, the tumbling would be unpredictable so you'll have a large sheaf of possible trajectories depending on how the payload gyrates during entry and ends up exitting the atmosphere, likely to re encounter it again with similar instabilities.)
In any event, you'd need a GNC with thruster package around center of mass, to do mid course corrections. And, in keeping with planetary protection protocols, you'd have to insure a clean miss with your mission operations team until your final commit to encounter, likely a month or so out. Oh, and you'll need DSN time to track/communicate such corrections and to monitor.
So much for bringing "Mars the planet" into the picture - work, work, work. Much better to just transit it's heliocentric distance from the sun, and not have to worry about all that and niggling things like being in the plane of the orbit, at a time when that might complicate ascent and ground tracking from the same location as launch ...