Interior white oak window boards - any special tips ?

[gcm]

Fitting American Oak interior window boards as replacements during a Rationel install.   Various sizes from (750mm-2900mm) x (240mm-460mm) x (25mm) thick

I need a bit of wise counsel with two issues to get it straight in my mind before I am stood there with the joiner looking at any exposed horrors.

Q1 Fixing

Are there any issues with using the right angle metal ties screwed up underneath the boards e.g. x3 (L CR R) for the normal sizes - or less/more) then to fix front to block below the aperture plastered over. This is an invisible alternative to top down drill screw and fill.  We are damaging plaster getting the old boards out) so could do it - just not clear if it's a good or bad idea - safety, rules, oak specific issues if any warping etc. etc.  Or what about screwed down mdf/timber batten below and glue the oak board to it as an alternative (depending upon what mess we find underneath what is there)

Q2 Finishing interior american white oak with a clear stain/coat

Would something like Sadolin Extra Durable Clearcoat do the job - sufficiently for UV (assuming I like the honey/yellow colour on a test patch) ?
Another alternative seems to be a Danish Oil such as Liberon (ditto)

I want to keep the colour light (for bouncing light in) and appearance - to see the wood, to have some UV protection against greying.  A little water resistance (any condensation and pots).

In a perfect world would go water based and have something lower voc for the job and venting later and not too difficult to apply - if such a thing exists

Thanks for any advice

[lizzie]

We used a Danish oil on our white oak boards.   Ours are unobtrusive and I dont really notice them as they are all low level.