Ardupilot Plane Project - Need help w everything

Hi everyone!

New person to ardupilot here
Thinking of some serious upgrades to my Tundra V2 - primarily to help me with landings, but also to have some interesting fun with Ardupilot.

Basically, can someone spend the time to show me various options for a complete rethink of my Tundra V2’s electronics?
(Also, new battery needed. Last ones got too puffy for my liking after some winter racing with an RC car. I can find my own battery, but what is a decently big one I could put in the plane to increase range?)

Needed:
Some form of “beginner mode” stabilization (like drones) to help me with landings. I struggle to get the fairly big plane down in a road, it is long but ditches to left/right. Haven’t found suitable fields yet with grass short enough for plane to not flip on takeoff/landing. (FYI: road is a dirt road surrounded by fields, several kilometers away from my home)

Decently accurate GPS - capable of missions and landings on that road, as well as takeoffs (I want to play with auto landings and auto takeoffs)

Barometer
Speedometer (pitot tube? not sure of the correct word)
Radar altimiter (Yeah, I know landings can be done with just GPS and barometer, but I need accuracy)

Some way of streaming info from all aforementioned things to OSD (if I am in the wrong forums, plz tell me which are the right ones. I have OSD on a small drone but no idea how to put it on my planes)
Battery voltage monitor? Again, not sure how this works.

Finally, an ardupilot board.

Please assume I am more-or-less a newbie to ardupilot. I know how to fly my planes via FPV or line-of-sight, but I struggle with landings sometimes. The OSD elements will help with manual landings, and I have allways wanted to try automated missions.

Is the Tundra V2 even a good plane for this? I can get another plane, but I love my Tundra V2, even with my landing struggles (pain point is that if I come in too fast, it flips on its nose. Not nice. If I come in too slow, it stalls.)

About ELRS - once had the connection cut out on my Frsky connection. Range is kinda limited on Frsky but ive seen my ELRS drones have no issue.

If anyone is really curious, I kinda want to add another servo to my plane to drop my Meteor 75 drone mid-flight BUT I don’t have 2 remote controls, so the Tundra would have to be flying an automated mission.

Clarification:

For battery, I just keep my flights short.
And I try to not go far from takeoff point as I have no GPS.

for GPS you could go with Neo 8m.

Neo 8m sounds ok.
RTK GPS is worth it?

Road is like 3m from one side to the other (borders have rocks, bumpy terrain, and some kind of very tall grass which the wings would catch)

EDIT: Can Ardupilot land reliably within 3m (left/right) on a road w this GPS, and stay on it while slowing down?