Pine log bridge

[ktm250rider]

Ive got a 8-10 foot brook to cross to get to most of my property with my JD 4510 utility tractor. I currently have a couple of 30 foot long 30" diamter pines that I was planning on using as beams. They both have a fork in them at about 10 feet from the end which i figure would add for some stability.
My problem is they are not even from side to side. I would like to have the deck as flat as possible without any rollers in it.
Ive thought about trying to get them somewhat uniform with my chain saw (no mill) just rough hand.
My niehbor is sending some logs to be milled for his garage. Would it be more advisable to see if I can get those two logs on the truck and get them milled square?

 

[clearance]

I would just snap lines with a chalk line, make cuts down to those lines with my saw every 6" or so and then chunk out the pieces with my axe. Good enough. May be a good idea to make little gaurdrails, spiked throught the deck into these logs.