Provided you have enough current rating on your Lithium Ion cells landing 1.2kg with a quad setup is easy. You should be able to do it with a set of KDE 1806 on a 5x3 prop with 2:1 thrust to weight ratio and hover at around 20A. Two KDE 1806's plus 2x 20A ESC's and flat bar CF quad arms should only weigh around 120g each, so 240g for the whole QP setup. Another option is a parachute...but you won't have much in the way of landing accuracy. High pitch reverse thrust might be another option for landing, or belly stitter config on a wing.
Solar is possible, Banggood have some MPPT controllers for around $70. PV cells are an issue on the wing, legit Sunpower ones bend at least and have good conversion. Would need to know what the cruise requirement is of the plane to see if solar is worth it. 1.2kG with solar is very lightweight for a 2m foamie, Radian weighs 980g by itself? Even 4s2P battery is 400g. So maybe more like 1.6kg? Soaring might be easier and lighter to make proper use of and like solar would depend on flying weather.
The other question is if you really need endurance or range. They aren't the same thing. If you need endurance then solar power becomes more likely, if you need range it's less so unless you can sustain flight with solar power alone. It also strongly influences the optimisation of the forward motor/prop combo. So you'd be able to do one or the other. The quadplane takeoff (and landing) can also improve the flexibility you have in selecting the best forward motor/prop combo as you can neglect static thrust for forward flight takeoff.
On the avionics and imaging side that's all possible, and reducing the size and weight of the required payload to a minimum is essential in reaching endurance and range. Gimbals etc add weight. The other question is if you need endurance do you need comms range, like LTE modem. If so then a CC (Companion Computer) is required, but a raspi zero W could do all the required, including 8MP imaging, FHD video FPV over wifibroadcast running Maverick. Will also provide a telem path for GCS, and cost less overall. Otherwise, LTE range is limited only by your aerial cell coverage (as in it can be on the other side of the planet!), data is fairly cheap in most places, and you can easily use Zerotier to punch through the Mobile phone NATs to connect from and to anywhere.
That should get you started at least.