Well, I'm not an electrician, or in the position to recite code, BUT, I just had my 100/60/100A service upgraded to 200A underground, in which I buried my phone and cable in the same trench with. I followed the phone/cable/POCO company recommendation of 12" inch spacing from feeders. Cable and phone were run together. Can't say its legit everywhere, but it worked here. What a mess backfilling that trench.
The service disconnecting means shall be installed at a readily accessible location outside or the nearest point of entrance of service conductors ( 230-70(a) ). Rule of thumb 2 times the length of Service Panel or no distance greater than five feet, which ever distance is the shortest from the out side of building. So in a lot of cases that service disconnect will need to be outside.
Depending on the dwelling type (Standard house) NOT PREFAB or Modular,in my area northern minnesota,you may run unfused to your meter base then on to your service. You need to have 3 ft of a panel clearance and make it readily accessible RE: Dont hang it over a sink,dryer,washer,water heater,furnace...I have seen them all.
Place the meter in a readily accessible location for your meter man, RE: OUTSIDE.
What I have been installing in rural areas is a Farm panel with a built in meter 200 amp feed through, and eight breaker locations ,I place that out at the pedestal,sub feed all of the out buildings, the garage, the well and the septic. The meter man can read the meter at the end of the driveway.
Now as far as I know the panel clearances cover you on the boiler,The reason the metering can't be down there is you cannot run your unfused service conductors through the house, as well as you cant have the meter inside. I have worked joint plant construction (Where telephone cable and power are run in the same trench) BUT WE HAD A DEEP TRENCH, Don't think you can dig a 2 ft trench and throw it all in, Your phone is the one that suffers the most. Especially when they are run parralel. Its done all over 12 inches of clearnce from feeders but, I just don't recommend it myself. If your cutting one trench, cut two and no troubles.