I don't find it much of an issue - just take the centre diff out completely (4 screws), and you have unrivalled access to the mesh - you can see it far better than on a nitro, and makes meshing very easy. The Elite is quicker, but the RCM is hardly slow - I took much longer doing my nitro mesh than the electric.
The RC-M tray is 50x145mm - which should be large enough for almost any battery (mainly length restricted though). They can also do a custom job which'll be the exact right size for your pack - this is how I've always had my trays - to exactly fit a certain battery. They do come with straps.
For reference - here's the
Hyperion data sheet.
Also, you must remember that the Elite 'Conversion' was something that Mr Elite (Brandon Wong) made for a friend, only the motor mount is available yet as far as I know. There's nothing stopping you from using the Losi's radio box on your conversion, or the RCM box for
the D8/T conversion.
On a slight off topic note, look how nice the new
XT8 conversion is! Drools....