In CT LBB 2 1977 I concluded that the Jump Drive was a specialized power plant that was not designed to run a ship's life support, computer, other electronic/electrical systems, maneuver drive, and weapons. Unfortunately, CT LBB 5 HG 5 added the requirement that the power plant number must be at least equal to the higher of the jump drive number or the maneuver drive number. MT Referee's Manual page 58 states that "jump drives are themselves a special high-yield power plant linked to an integral net in the craft's hull for initiating and maintaining the jump field."
If the jump drive's power plant is also supposed to take over the capabilities and duties of a standard power plant, per CT Supplement 7 page 9, to run life support, computer, and electronic/electrical systems then the cost, fuel requirements, and tonnage should probably go up too, but I'm not sure how much.
If I'm not out to lunch using CT LBB 2 1977 without a power plant and maneuver drive my calculations for the CT Supplement 7 X-boat is J4 Type-B drive at 15 tons with 40 tons of fuel, a 20 ton bridge, a 1 ton Model/1bis computer, two 4-ton staterooms, and 1 ton of cargo capacity which leave 11 tons. The X-boat has a maximum range of 4 on 40 tons of fuel and 3 days.
Since the CT LBB 2 power plant only has to be either the same type or a higher type than the maneuver drive I'm going to install a Power Plant-1 Type-A which is 4 tons. The power plant Type-A requires 10 x 1 = 10 tons of fuel for 4 weeks. The combined total exceeds the 11 tons available. I'm going to reduce the 4 weeks of operation to 3 weeks which I think requires 10 x (3 / 4) = 10 x .75 = 7.5 tons of fuel, which is still over the 7 tons by 0.5 tons. Cutting the time of operation to 2 weeks requires 10 x (2 / 4) = 10 x .25 = 2.5 tons of fuel. The combined total of a 4 ton Power Plant-1 Type-A plus 2.5 tons of fuel for 2 weeks of operation is a total of 6.5 which leaves 4.5 tons available to add to the cargo capacity or maybe add another stateroom.
I don't think that the jump drive needs to add the full 4 tons of the power plant-1 type-A, but I do think it should be more than 15-tons, but the fuel requirement should be the same as for a power plant-1 type-A. The cost of the jump drive should also go up. Looking at the CT LBB 2 1977 Drives and Power Plants table on page 11 the change from a power plant type-A to type-B is 3 tons and the cost is MCr8.0. My thought would be to increase the J4 Type-B drive's mass by 3 tons and MCr8.0 since it is adding the functions and capacities of the power plant.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
IF we look at the design systems as dictated by 3I rules & regulations rather than the 'Real World'(tm), we can then assert that the ScoutService has a waiver & just go ahead & design an Xboat w/o PPlant or MDrive.
Perhaps the reason for the 'starships must have a Jdrive, Mdrive, & PPlant' regulation is to provide a higher level of 'safety' thru redundancy or whatever?
Similar to the myriad of 'safety' regs that the US federal gov imposes on auto makers that wish to sell their products w/i the USA.
So, just go ahead & design it with just a Jdrive (I'd use CT LBB5 HG as this is intended for a paramilitary org but I think CT LBB2 could work too), leave out the 'stateroom' cuz' the 'bridge' is actually a modified design which allows single or, in a pinch, double bunking, add some extra fuel for non-jump power, &/or assume that there's always some left over in the Jdrive due to Imperial regulatory 'safety' requirements.
A lot less hassle that way.
p.s. Another idea would be to just drop the 'bridge' & state that the 'stateroom' is a custom mod (5-8 dT's?) that also includes a very minimal (definitely NOT up Imperial standards but allowed under a waiver) suite of ship controls. After all how much does an Xboat really need to be actively 'piloted'?
=========================================================================================