Hi Brad,
Marcus probably knows his stuff, getting the Queen to foot the bill for a good education, Signals and all.
I've had a few fingers in the radio pot for about 40 years, and play with ex-mil stuff as it turns up. Can't tell you the tonnage of boatanchors I've lugged home from Dayton over the years.
Your right on as to the space limitations in a 110SW, and unless you want to load up the back with equipment, using it stationary mobile, the best way is one of the many rice boxes available today. Kenwood, Icom, Yaesu, and Alinco make pretty decent packages, some with more bells and whistles than others. The Icom 706 MkIIG goes all the way from HF to 450, but when it goes down, it ALL goes down.
I run a basic Alinco DJ70 Hf rig with a High Sierra antenna
http://www.w6up.com/. The High Sierra is a 'screwdriver' motor driven adjustable coil, base loaded, and tunes 80-10, though with a 110" whip I can also do 160. (I run a seperate dual bander for 2m and 70cm)
Like the Defender itself, the radio install is always in a state of flux, sort of a work in progress. I just added a JRD auto tuner, because even the though the High Sierra is tunable, it's null is pretty sharp, so if I'm in the neighborhood, I let the JRD find the best match.
ALL EFI systems have their interference weaknesses, and keep in mind that interference is a two-way street, RF emmissions from the radio getting into the engine management computer, and vice versa.
I agree with Marcus that the 300Tdi is the best platform, no worrys about RF in either direction.
My 110 is a 4.2 with Lucas 14CUX, and I get the usual noise from the charging system(easiest to remedy) but no problems with radio/ECU in either direction. I know that the TD5 ECU handles alot more chores, so I couldn't say if it is more or less suseptable to RF problems. I do know, having just come back from Tortola, that my friend who owns the LR dealership in the BVI is still able to supply the 90 and 110 in 300Tdi, so they may be a special order item, since I thought that LR only supplies them in TD5 for general market.
The only thing I can suggest, apart from good grounding (sorry Marcus, I meant 'earthing') is good quality connectors in the RF line, and a well matched antenna. My experience is that 40 and 15 (more so than 40) are the most problematic with stray RF. I'm only running 100 watts, but a half gallon or gallon will surely screw the best of systems, at least when underway. I do 90% of my operating stationary, the Defender being so damned noisy anyway.
I love 17m, and regularly chat with G4DKM, when he parks on the beach in Blackpool, though can't say I've worked VK from the mobile.
Cheers, 73s, all that stuff. Terry K1ebs