How to get rid of a rat in new-to-me truck

[MARKDTN]

I inherited a truck that has been sitting since at least 2008. I knew when I got it that mice had been in there as there was a lot of nesting material. But it was cold and so I assumed they were gone. Brought it home 100 miles and parked it on the trailer in my lower yard. It sat 2 weeks and last Saturday I decided to clean it out. Wearing gloves and a mask, I open both doors and took a leaf blower from the drivers side and blew as much as I could out. I folded down the seat and that is when I saw the rat. The body is at least 6-8" long. It is the size of a small rabbit or big kitten. I took the leaf blower and blew at him hoping he would go out the open door. He did not, he went up the passenger side pillar post inside. So I cleaned out the fluff behind the seat. I went and bought a box of 3 mouse poisons. Saturday night I took the top off so it just had a block of green poison exposed. Sunday morning the entire box was gone. Saturday night same thing-top off box, place behind seat, Monday morning it was gone. Monday night I put the last one out but left the top on. Tuesday morning it was gone too. Tuesday afternoon I took the leaf blower and blew out the cab again. I saw the rat go under the dash behind the glove box. I removed the seat and found that is where he has been living. I did find the 3 boxes of poison and he did nibble pretty good on 1 block. I put all the poison back in the middle of the floor. It is raining a lot here and my yard is a pond now. So:
1-How do you get rid of a large rat? My dad says carbon monoxide from a lawnmower. Maybe antifreeze? What if he climbs up on top of the headliner and dies? I had my 20-gauge yesterday but he didn't get out of the cab.
2-I am concerned about Hantavirus or similar. This rodent has been in there a long time. How can I get this truck clean enough to drive again? Lysol everything?
3-what if he decides to come to the house now that I have removed his nest under the seat? My wife is very afraid. The trailer is probably 40' from the back door. Its a pond now so I can't get down there to move the trailer without tearing up the lawn badly.
Help! Thanks