Mike, I have profile models with the tanks mounted on either side of the fuselage.( to keep the nose short) I run Sullivan slant tanks with the pickup line with a clunk. I run muffler pressure on all my setups. I have Zero problems. Been doing it this way for years now. I'm building a twin right now that has the tanks on the opposite sides of the engine to keep the engines closer to the wing. I dont anticipate any issues....Gene

I haven't noticed a tremendous difference with mounting the tank on the inboard side of the fuselage; to the extent that I can tell a difference, it's better.  You do have to adjust the engine a bit differently on the ground, as it richens up when it starts going (or at least leans out less).  This is one of those "I haven't noticed much" things, because my usual approach to a first flight on an airframe is to aim for too rich, and then sneak up on the engine's happy spot on subsequent flights.

(Edit) The theory on the inboard tank setup is that because there's some head between the tank and the engine, it's actually pressurizing the fuel a little bit due to centrifugal force (or centripetal acceleration -- take your pick).  That pressurization goes up with flight speed, so if you're adjusted a bit rich of high speed, slowing down leans you out and speeds you up, while speeding up richens you up and slows you down.  I've only done this on pressure tank setups, but it certainly seems convincing -- and it makes finding a home for a tank on a short-nosed airplane much, much easier.

--snip--
 With outboard tank, you must set the engine rich before take-off. It's difficult to get a reliable RPM reading like that, so you loose in the precision of repeatability. That is one.
 With inboard tank, you must set the engine lean before take-off, and when you overheat the engine, it's also not in the most stable condition, and also it takes a longer time to stabilise to flying temperature. That is two.
--snip--
In practise, we have found a good starting point for tank lateral position to be so, that the pickup point (outer rear corner of tank) is 6...8mm more "out" than the end of fuel post in venturi, measured from fuselage centreline.
--snip--

One of these days I want to build a profile with a good-sized hole behind the engine, and an inboard mounted tank with a sump that sticks through the hole.  Then you could have your cake and eat it to.