Can I pay Czech conductor on board a Nuremburt-Prabue train in euro?

My frient and I plan to take a train from Rothenburg to Prague using Bavaria-Bohemia Ticket. So, I will have to buy tickets from Plsen/Pilzen to Prague from Czech conductor on the train.
When we arrive Munich, we will go straight to Fussen and then Rothenburg. I'm not sure that I can get some Czech crown there.

Can I buy these tickets onboard the train using Euro?
Can I buy Czech crown at Munich airport at 6.00am? Or, at Munich HBF since I will have to wait for a train to Fussen there. Or anywhere else near Munich HBF around 8.00-8.30 am.
I think about 500 Czech Crown should be enough for tickets for 2 and day passes in Prague.

My concern is what will a Czech conductor do if I am on board the train without any Czech crown to buy a ticket?.

Thanks

can, but its not WISE
as most of those youngies seem so unaware of it: you can simply, BUY that ticket borderstation-into any station in CZ you want at ANY manned German (or in fact ANY continental-european manned international-tickets doing station), same time as you buy that bayern ticket.
DB also sells Praha specials from Munchen/Nurnberg or regensburg. these are returns
you CAN exchange € for CzK, at a big loss, at any REISEBANK in all main German stations. I dont know when they open-mostly like 8.00 or 9.00 mornings. the Bayern ticket is also NOT valid before 9.00 on mon-fri.
you can also simply go out in Plzen, find the ATM, get the CzK at a decent rate, maybe even peek into Plzen and the big tesco overneath for shopping and take next train-1 hr later. the train from DE stays also some 12/15 mins-the locomotive has to be changed.
you CAN also-if you come back same way, buy that Bayern-or weekendticket for DE at the TRAVEL agent UPstairs/outside in the now under heavy reconstruction Prahy hlavni nadrazi. pay in CzK. the studentagency bus Plzen-Prahy is quikcer, much cheaper, but does NOT serve any of the vlakove nadrazi=train stations in eihter city

As bmta says it's not the best option as you can be overcharged (or at least I was doing exactly the same thing between Austria and Czechia a few years ago)...if you have time, I'd advise you to break your journey at Plzen for a few hours anyway and have a look around the city and carry on from there...

Wow!! Thanks,
I've never thought about breaking a journe at Plzen.

I broke my own journey to Munich from Prague and back a couple of times in July and spent 2 nights in Plzen...great place to spend some time...if you're just passing through you can have a dander around town and then relax with a beer or coffee in the main square (Namesti Republicky) or check out the marvellous pure, unfiltered beer at the 'Na Parkanu' pub, just off the city centre...if you have more time you can visit the Pilsener Urquell brewery and do the tour there...Na Zdravi...

another option to stop is town domazlice. it is lovely town and it is first stop after borders. good chill out for one night...