Roll off truck questions

It’s just odd that most every YouTube video I see, or trucks driving down the road don’t have the vertical piece. Could it be welded on after the fact? Dealer sent me this. Looks like the vertical piece is welded on and appears to certainly be inside outside hoist?
I’m pretty sure I went w outside rail hoist

 

I was talking to a localish company the other day, they are upgrading one of there trucks and it’s for sale. I’m going to look at it
It’s a 02 Mack rd688s
Very clean looking truck from the pictures they sent me. Only thing is it is a TRI-AXLE/ lift axle. Which I think it going to be overkill for me starting out but I figure I’m going to atleast look at it. Just wish it wasn’t a TRI-AXLE since I know it’s a little too big for starting out

 

The TRI is certainly a big truck, but can haul 10-30 yard cans so the capability is there. If the wheelbase of a tandem is the same then I shouldn’t have too many problems with delivery’s. I’m going to go back this weekend to look at it again, but seems to be a good first truck.
I figure fuel mileage is already going to be crap anyways so will the pusher really make a difference? Guessing around 5-6mpg probably?

 

I want to buy a capable truck to start out, I want something with the capacity for the future. I’m thinking if the inspection on the tri goes good I’ll probably buy it. Around here all of the newer trucks are tandems and or single axles. Republic and wms and the smaller local guys older trucks are mostly tri axles, not sure if there’s a reason for that

 

So doing a lot of thinking, I want a truck that is going to be capable for different size bins, but I don’t want something that is going to limit me with residential renters. The point I’m seeing is for neighborhoods it’s going to be tight with the tri I’m looking at. I think it may be an issue getting the truck into driveways, maybe I’m just overthinking it but that’s something I now need to consider. Need to make sure I’ll be able to get into driveways. What do you guys think? Should I try to find a single axle/ smaller truck that should still be pretty capable or go with the tri and make it work?