Round tube & chassis mods... a world of pain?

[TQ_uk]

Ok, to set the scene, I can now nearly see the garage floor post house move & seriously thinking about starting a build.

For perverse reasons best known to myself I fancy increasing some of the dimensions of the 'book' chassis & materials.

Can't help thinking the standard tubing looks a bit 'weedy', aesthetically as opposed to physically, so I'm considering going for deeper rectangular base rails, and swapping much of the remaining tubes for larger OD tube (say 38mm) but of a similar final chassis weight (ie tube wall thickness may come down a bit).

I'm also considering increasing the wheelbase slightly.

Now ignoring the fact that roadster bodywork won't necessarily fit (I've a few ideas of my own here), my questions are this:

a) am I making life (too) difficult for myself, and should just stick to the book plans?

b) what effect on steering geometry be if I stretch the wheelbase say, another 100mm or so?

c) Will seamed tube (ERW?) be an ok replacement for square section rather than the expense of CDS?

I realise in areas where stressed brackets (eg wishbone) are attached the wall will have to be of a suitable thickness.

Any opinions from your experiences? This is my first build, so I expect some 'keep it simple' response but not too phased by a bit of experimentation for the cost of some steel & welding supplies